Data 1
If the sample size (N) for a one-sample t test was 81, how many degrees of freedom would that t test have?
80
Which of the following actions would increase statistical power for a z test? Please choose all correct answers below. For each option, please assume that only the factor mentioned changes (i.e., all other factors remain constant). - Increase alpha from 0.05 to 0.10. - Increase the sample size, - Increase the population standard deviation. - Decrease the mean difference between the relevant sampling distributions, thereby causing the distributions to overlap to a greater degree
- Increase alpha from 0.05 to 0.10. - Increase the sample size,
Which of the following are assumptions of the z test? Please select all correct answers. - The independent variable is measured as a scale variable. - The dependent variable is measured as a scale variable. - Participants are randomly selected from the population. - The population of interest is normally distributed.
- The dependent variable is measured as a scale variable. - Participants are randomly selected from the population. - The population of interest is normally distributed.
Which of the following statements are true for a distribution of means? (When answering, please assume that the sample size for each mean is equal to 80 and that all scores are drawn from the same population of scores). Please select all correct answers. - The distribution of means has less variability than the corresponding population of scores. - The distribution of means has more variability than the corresponding population of scores. - The distribution of means has the same mean (average) as the population of scores. - If the population of scores is not normally distributed, the distribution of means should be more normally distributed than the population of scores.
- The distribution of means has less variability than the corresponding population of scores. - The distribution of means has the same mean (average) as the population of scores. - If the population of scores is not normally distributed, the distribution of means should be more normally distributed than the population of scores.
The external validity (generalizability) of the results of a study can likely be improved... Choose all correct options that correctly complete the sentence fragment above. -by using a volunteer sample instead of a random sample. -by using a random sample instead of a convenience sample. -through conducting replications. -by using a sampling strategy in which every member of the population has an equal chance of being included in the study (i.e., included in the sample).
-by using a random sample instead of a convenience sample. -through conducting replications. -by using a sampling strategy in which every member of the population has an equal chance of being included in the study (i.e., included in the sample).
Please consider the following information: Sample mean (M) = 50 Population mean (µ) = µM = 49 Sample standard deviation (s) = 4 Sample size (N) = 25 Based on this information, compute the effect size measure, Cohen's d. Please include at least two decimal places when reporting your answer.
0.25
Imagine that a researcher is conducting a paired-samples t test. She finds that the sample mean difference is 3.665, the standard deviation of the difference scores is 9.334, and the sample size is 75. The researcher is also using a typical null hypothesis that proposes no differences between the relevant population means. Under these circumstances, what is the value of Cohen's c? Please retain a minimum of three decimal places for all steps (if relevant) and provide a minimum of three decimal places when writing your answer.
0.393
Consider the following information: Population mean = 9 Population standard deviation = 8 Sample mean = 15 Sample size = 81 Based on this information, what is the corresponding measure of effect size, Cohen's d? Please type your answer below using digits. If decimal places are relevant, please include at least two decimal places in your answer.
0.75
Imagine that a researcher studies a population of 1000 people. Within this population, heights (measured in inches) are normally distributed. Please assume that the mean height for this population is 68 inches with a population standard deviation of 4 inches. Under these conditions, what z score would correspond to a height of 71 inches? Please report the correct z score below with two decimal places (if relevant).
0.75
Please consider the following information: Sample mean (M) = 78.6 Population Mean (4) = 77 Population standard deviation (0) = 2 Standard error (04) = 0.4 Sample size (M = 25 Based on this information, calculate the effect size, Cohen's d. Please provide at least two decimal places when reporting your answer (if relevant).
0.8
Imagine that a normal distribution has the following properties: population mean = 50, population standard deviation = 10. What is the z score that corresponds to a raw score of 61 from this distribution? Please type your answer below using digits. If decimal places are relevant, please include at least one decimal place in your answer.
1.1
Please consider the following information: Sample mean (M) = 50 Population mean (µ) = µM = 49 Sample standard deviation (s) = 4 Sample size (N) = 25 Based on this information, compute the t statistic for a one-sample t test. (You may need to compute some other values before computing the t statistic itself). When reporting your t statistic, please provide at least two decimal places.
1.25
What is the standard error for a one-samplet test when the sample standard deviation is 7 and the sample size is 29? Please provide two decimal places when reporting your answer.
1.3
Imagine that a researcher conducts a one-tailed z test with an alpha level (also called a p-level) of 0.05 (5%). What is the absolute value of the critical value for the corresponding hypothesis test? When answering, please provide at least two decimal places (if relevant).
1.64
What would be the critical value for a one-tailed, one-sample t test with a sample size of 41 (N = 41) and an alpha level (p level) equal to 0.05 (5%)? Please provide at least three decimal places when reporting your answer. Please also provide only the absolute value of the answer (i.e., don't include a "+" symbol or "-" symbol).
1.684
Imagine that a researcher appropriately collects data from 100 people from a particular population for variable X. He obtains a mean of 45.9 from these 100 people. He also knows that the population mean for variable X is 45 (μ=45) with a standard deviation of 5 (σ=5) Using this information, compute the z statistic. Please report the correct z statistic below with two decimal places (if relevant).
1.8
When considering a z score of -0.29 from the standard normal distribution, what percentage of the distribution of scores falls between the mean and that z score? Please provide your answer as a percentage with two decimal places. (You do not need to include the percent symbol). You should use the z table when answering this question.
11.41
If you were correctly told that a population of 400 people had a variance of 225 for a particular variable, what would the corresponding standard deviation be for that variable (rounded to two decimal places)? A) 15.00 B) 21.23 C) 7.20 D) The answer can not be determined, based on the information provided. E) None of the above
15.00
Consider the following information: Sample size = 49 Mean of the sampling distribution of means = 28 Population standard deviation = 14 Sample mean = 32 Based on this information, what is the corresponding z statistic? Please type your answer below using digits. If decimal places are relevant, please include at least two decimal places in your answer.
2
What would be the critical value for a two-tailed, one-sample t test with 28 degrees of freedom (df = 28) and an alpha level (p level) equal to 0.05 (5%)? Please provide at least three decimal places when reporting your answer. Please also provide only the absolute value of the answer (i.e., don't include a "+" symbol or "-" symbol).
2.049
What is the absolute value of the critical value for a one-tailed, single-sample t test when the sample size is 27 and the alpha level (or p-level) is 0.01 (1%)? Please provide three decimal places when typing your answer.
2.479
When considering z scores of ±1.25 from the standard normal distribution, what percentage of the distribution of scores are at least as extreme as those two z scores (i.e., at least that distant from the mean)? Please provide your answer as a percentage with two decimal places. (You do not need to include the percent symbol). You should use the z table when answering this question.
21.12
Please calculate the sample standard deviation for the following sample of five numbers: 2, 3, 7, 8, 10 Please provide at least two decimal places when reporting your answer.
3.39
Imagine that a researcher is conducting a paired-samples t test. She finds that the sample mean difference is 6, the standard deviation of the difference scores is 20, and the sample size is 194. The researcher is also using a typical null hypothesis that proposes no differences between the relevant population means. Under these circumstances, what is the value of the paired-samples t statistic? Please retain a minimum of three decimal places for all steps (if relevant) and provide a minimum of three decimal places when writing your answer.
4.179
Please consider the following information: Sample mean (M) = 78.6 Population mean (4) = HM = 77 Population standard deviation (0) = 10 Standard error (04) = 1 Sample size (M) = 100 Based on this information, how much power would a researcher have to correctly reject the null hypothesis for a one-tailed test? For the purposes of this question, please make the following three assumptions: 1) The null hypothesis really is false. 2) The researcher is appropriately conducting a one-tailed z test with an alpha level of 0.05. The corresponding critical value that the researcher uses is z = 1.65. 3) The researcher is looking in the correct tail of the distribution. In other words, the researcher predicted that the sample mean (78.6) would be greater than the mean of the comparison population (77). Please report the power of the corresponding z test as a percentage with at least two decimal places. (You do not need to include the percent symbol with your answer).
48.01
Imagine that you have a normal distribution of scores with the following properties: Population mean = 50 (μ=50) Population standard deviation = 5 (σ=5) What is the value of the raw score in that distribution that would leave 20.05% of scores above it? Please provide at least one decimal place when reporting your answer.
54.2
When considering z scores of ±0.85 from the standard normal distribution, what percentage of the distribution of scores falls between those two z scores (i.e., +0.85 and -0.85)? Please provide your answer as a percentage with two decimal places. (You do not need to include the percent symbol). You should use the z table when answering this question.
60.46
Please consider the following information: Sample mean (M) = 64 Population mean (µ) = µM = 61 Sample standard deviation (s) = 8 Sample size (N) = 25 Based on this information, please compute the corresponding 95% confidence interval. Please type the lower boundary of the confidence interval as your answer. Please include at least three decimal places in your answer, if relevant.
60.6976
When considering a z score of -1.15 from the standard normal distribution, what percentage of the distribution of scores falls above that z score? Please provide your answer as a percentage with two decimal places. (You do not need to include the percent symbol). You should use the z table when answering this question.
87.49
Imagine that a standard deviation is equal to 9.00 raw units (meaning 9.00 units in the original metric of measurement) for a population of scores. This standard deviation means that, on average, the scores in the corresponding population deviate... A) 3.00 raw units from the mean. B) 9.00 squared units from each other. C) 9.00 raw units from the mean. D) 3.00 raw units from the most extreme score. E) None of the above.
9.00 raw units from the mean.
Consider the following means and sample sizes for two independent samples (with the samples being denoted by the subscripts "*" and "*): Mx = 5.899 My = 3.296, nx = 16. ny = 16. If the standard error (Spifference) is 3.172, what is the the upper boundary of the corresponding 95% confidence interval? Please use a typical null hypothesis that predicts no differences between the two populations when computing your answer. When calculating your answer, please ensure that you subtract the mean for group Y from the mean for group X (i.e., Mx - My). Please also retain three decimal places for all steps (if relevant) and provide three decimal places when reporting your answer.
9.083
Please consider the following information: Sample mean (M) = 95 Population mean (4) = 100 Population standard deviation (0) = 18 Sample size (M = 144 Based on this information, what is the lower endpoint (denoted Mower in the textbook) for the corresponding 95% confidence interval? Please include two decimal places when reporting your answer.
92.03
When considering a z score of 1.42 from the standard normal distribution, what percentage of the distribution of scores falls below that z score? Please provide your answer as a percentage with two decimal places. (You do not need to include the percent symbol). You should use the z table when answering this question.
92.22
Which of the following graphs would be appropriate for examining a nominal independent variable, along with a scale dependent variable in the same graph? Choose the best answer. A) A dot plot B) A bar graph C) Both options above would be appropriate. D) None of the options above would be appropriate.
A bar graph
Which of the following visual displays would be appropriate for graphing a single nominal variable and a single scale variable in the same visual display? A) A dot plot B) A histogram C) A bar graph D) All of the above C) None of the above
A bar graph
Imagine that you are conducting an experiment in which each participant is randomly assigned to one and only one level of the independent variable throughout the course of the experiment. Which term below would best describe this experimental design? A) A correlational study B) A between-groups research design C) A within-groups research design D) A confounding variable design
A between-groups research design
Which of the following displays would allow you to see both the shape of a distribution and the individual data points at the same time? A) A histogram that uses intervals B) A frequency table C) A grouped frequency table D) A dot plot
A dot plot
Imagine that the following item is included in a survey: "Please indicate the number of days that you attended in-person class meetings this week. If you attended the class in-person for any amount of time on a particular day, please treat that day as a full day of attendance." What type of variable would be produced by accurate responses to this item? Please choose the most complete and accurate option below. A) A nominal variable B) An interval variable C) An ordinal variable D) An ordinal variable that is also a scale variable E) A ratio variable that is also a discrete variable F) None of the answers provided above are correct.
A ratio variable that is also a discrete variable
Imagine that a normal distribution has the following properties: population mean = 50, population standard deviation = 10. What is the raw score that corresponds to a z score of -0.65 from this distribution? A) 43.50 B) 55.00 C) 57.50 D) 45.00 E) None of the above
A) 43.50
Imagine that you wish to compare a sample mean to a population mean to decide if you can reject the hypothesis that My = M2. Assume that you have the following information: N = 45, M = 10, a (sigma) = 2, = HM = 8. Which of the following types of tests should you use? A) A z test B) A one-sample t test C) A paired-samples t test D) An independent-samples t test E) None of the tests listed above could be appropriate.
A) A z test
Imagine that a researcher correctly computes a paired-samples t statistic using JASP. She finds that the p value reported by that program is 0.003. Based on this information and the rules of hypothesis testing, what decision should the researcher make for a two-tailed hypothesis test with an alpha level (p level) of 0.05 (5%)? When answering this question, please assume that the researcher is using a typical null hypothesis indicating no differences between the populations. A) Reject the null hypothesis B) Fail to reject the null hypothesis C) Accept the alternative hypothesis D) Reject the alternative hypothesis E) The answer cannot be determined based on the information provided.
A) Reject the null hypothesis
Imagine that a researcher obtains a sample mean of 38 with a sample size 100 (N = 100). Additionally, please assume that the relevant population mean is 34 and that the relevant population standard deviation is 15. Under these circumstances. if the researcher conducted a two-tailed z test with an alpha (or p level) of 0.05 (5%), what conclusion should he or she reach, based on these data and the rules of hypothesis testing? When answering, please assume that the researcher is using a typical two-tailed null hypothesis indicating that there is no difference between means... A) Reject the null hypothesis B) Fail to reject the null hypothesis C) Reject the alternative hypothesis D) There is not enough information to reach any of the conclusions listed above.
A) Reject the null hypothesis
Imagine that a researcher wants to calculate a 95% confidence interval to accompany an independent-samples t test. Under those circumstances, which of the following terms would be used in the 95% confidence interval equation? A) SDifference B) S^2 difference C) Spooled D) S^2Pooled E) None of the above
A) SDifference
Imagine that a researcher wishes to conduct an independent-samples t test with data from "group X" and "group Y" (denoted by the subscripts "X" and "Y"). The sample variance of group X is 10 and the sample variance of group Y is 12. If there are 41 people in group X and 61 people in group Y, what is the standard error (Sdifference) for the corresponding independent-samples t test? (When computing your answer, please round to three decimal places at all times). A) Sdifference = 0.676 B) Sdifference = 1.323 C) Sdifference = 0.432 D) SDifference = 2.918 E) None of the answers above are close to the correct answer (i.e., within 0.1).
A) Sdifference = 0.676
Consider the following information computed for differences between 25 pairs of scores: M = 5, s = 12. Based on this information, what is the t statistic for the corresponding paired-samples t test, when rounded to two decimal places? When answering this question, please use a typical null hypothesis indicating no differences between the populations. A) t= 2.08 B) t=0.42 C) t=10.42 D) t=2.91 E) None of the above
A) t= 2.08
Which of the following would be an example of an interval variable? A) The flavors of scoops of ice cream (e.g., vanilla, chocolate, strawberry) B) People's rankings for their favorite five genres of music C) People's heights measured in centimeters D) Air temperatures measured in degrees Fahrenheit E) None of the above
Air temperatures measured in degrees Fahrenheit
Which of the following options would be appropriate for displaying frequencies for a single scale variable? A) A histogram B) A dotplot C) All of the above D) None of the above
All of the above
Which of the following terms would correctly describe a normal distribution? A) Unimodal B) Symmetric C) Bell-shaped D) All of the above E) None of the above
All of the above
Choose the most complete and accurate response for the following sentence fragment: An outlier... A) is an extreme score (or an extreme combination of scores) that is very high or very low relative to the vast majority of scores in the sample. B) can have a strong impact on many statistics. C) may sometimes be omitted prior to data analysis. D) All of the answers above correctly complete the sentence fragment.
All of the answers above correctly complete the sentence fragment.
Which answer best describes a standard deviation? Read all answers and then choose the answer that is most complete and accurate. A) The standard deviation is the square root of the corresponding variance. B) The standard deviation is the typical amount that scores in a distribution deviate from the mean of that distribution. C) The standard deviation is a measure of variability. D) All of the answers above correctly describe the standard deviation. E) None of the answers above correctly describe the standard deviation.
All of the answers above correctly describe the standard deviation.
Which of the following is not a characteristic of the mean? A) The mean often requires an assumption of interval (or ratio) scale properties for valid interpretations about the meaning of the mean. B) The mean tends to be influenced by outliers (when they are present). C) The mean of a data set might not be an observed value within that data set. D) All options listed above are characteristics of the
All options listed above are characteristics of the mean
Imagine that the fuel gauge in a gasoline-powered vehicle moves from a reading of 100% full to 75% full as you drive the vehicle. However, when the gauge indicates that the tank is 75% full, it is actually only 50% full. Furthermore, the fuel gauge consistently gives a 75% full reading every time that the vehicle has a 50% full tank. Using the terms discussed in chapter 1 and in lecture, how could you accurately describe the fuel gauge? A) As a measure of the amount of gasoline in the vehicle's tank, the fuel gauge is both reliable and valid. B) As a measure of the amount of gasoline in the vehicle's tank, the fuel gauge is reliable, but not valid. C) As a measure of the amount of gasoline in the vehicle's tank, the fuel gauge is neither reliable nor valid. D) As a measure of the amount of gasoline in the vehicle's tank, the fuel gauge is valid, but not reliable.
As a measure of the amount of gasoline in the vehicle's tank, the fuel gauge is reliable, but not valid.
Imagine that a normal distribution has the following properties: population mean = 50, population standard deviation = 10. What is the z score that corresponds to a raw score of 42 from this distribution? A) 0.1.00 B) -0.8 C) 0.6 D) 1.00 E) None of the above
B) -0.8
Consider the following sample of five values: 2, 4, 5, 9, 10. Based on this information, what is the sample standard deviation (when rounded to two decimal places). A) 3.03 B) 3.39 C) 4.25 D) 11.5 E) 9.20
B) 3.39
When appropriately conducting a paired-samples t test, which of the following sampling distributions do we use? A) A sampling distribution of the mean B) A sampling distribution of the mean differences C) A sampling distribution of differences between means E) A sampling distribution of the pooled standard error D) None of the above
B) A sampling distribution of the mean differences
Imagine that a researcher appropriately collects data from 100 people from a particular population for variable X. He obtains a mean of 19.2 from these 100 people. He also knows that the population mean for variable X is 21.05 (4 = 21.05) with a population standard deviation of 10 (o = 10). If the researcher uses a two-tailed hypothesis test with an alpha level (or p-level) of 0.05 (5%), what decision should the researcher make when following the rules of hypothesis testing? (When answering, please assume that any relevant assumptions are met for this hypothesis test). A) Reject the null hypothesis B) Fail to reject the null hypothesis C) In order to choose one of the answers listed above, more information would have to be provided as part of the question.
B) Fail to reject the null hypothesis
Imagine that a researcher correctly computes an independent-samples t statistic using JASP. She finds that the p value reported by that program is 0.113. Based on this information and the rules of hypothesis testing, what decision should the researcher make for a two-tailed hypothesis test with an alpha level (p level) of 0.05 (5%)? When answering this question, please assume that the researcher is using a typical null hypothesis indicating no differences between the populations. A) Reject the null hypothesis B) Fail to reject the null hypothesis C) Accept the alternative hypothesis D) Fail to accept the alternative hypothesis E) The answer can not be determined based on the information provided.
B) Fail to reject the null hypothesis
Imagine that a researcher correctly computes the following 95% confidence interval for a paired- samples t test: 95% CI = [-1.035, 4.398]. Based on this confidence interval and the rules of hypothesis testing, what decision should the researcher make for a two-tailed hypothesis test with an alpha level (p level) of 0.05 (5%)? When answering this question, please assume that the researcher is using a typical null hypothesis indicating no differences between the populations. A) Reject the null hypothesis B) Fail to reject the null hypothesis C) Accept the alternative hypothesis D) Reject the alternative hypothesis E) The answer cannot be determined based on the information provided.
B) Fail to reject the null hypothesis
Please consider the following information: Sample mean (M) = 52 Population mean (µ) = µM = 49 Sample standard deviation (s) = 15 Sample size (N) = 81 If a researcher used the information listed above and conducted a two-tailed hypothesis test with an alpha level (p level) of 0.05 (5%), should the researcher reject a typical null hypothesis of no differences between population means, based on the corresponding t test and the rules of hypothesis testing? A) The researcher should reject the null hypothesis. Correct! B) No. The researcher should fail to reject the null hypothesis. C) There is not enough information available to make a determination.
B) No. The researcher should fail to reject the null hypothesis.
Imagine that a researcher appropriately conducts a z test and then calculates a corresponding 95% confidence interval. When calculating that 95% confidence interval, the researcher should center the confidence interval on... Please choose the best option that correctly completes the sentence fragment. A) The population mean (M). B) The sample mean (M). C) The population standard deviation:
B) The sample mean (M).
Which of the following correctly describes a standard error? A) The standard error is always equal to the variance of the corresponding population. B) The standard error is what we call the standard deviation for a distribution of means (from a particular population and with a specific sample size). C) The standard error must be greater in magnitude than the corresponding population standard deviation. D) All of the above.
B) The standard error is what we call the standard deviation for a distribution of means (from a particular population and with a specific sample size).
If Levene's test for equality of variances is "statistically significant," at an alpha level of 0.05 (5%), this means that... A) We probably have not violated the assumption of homogeneity of variance. B) We probably have violated the assumption of homogeneity of variance. C) We have violated the assumption that we have random samples. D) We have not violated the assumption that we have a normal distribution in the population. E) None of the answers provided above are correct.
B) We probably have violated the assumption of homogeneity of variance.
According to Cohen's guidelines for the effect sized, which of the following would be an example of a medium effect size? A) d= 2.00 B) d= 0.50 C) d= 0.80 D) d= 0.15 E) None of the above
B) d= 0.50
As the sample size increases, the corresponding t distribution... A) stays the same. B) more closely approximates the z distribution. C) becomes flatter near the center. D) becomes positively skewed. E) None of the options above correctly complete the sentence.
B) more closely approximates the z distribution.
Imagine that a researcher correctly conducts a two-tailed z test examining variable X with an alpha level (also called a p level) of 0.05 (5%). The researcher then correctly computes the following 95% confidence interval for variable X: (55.25, 59.75) Based on that information, would the researcher have enough evidence to reject the null hypothesis that the population he sampled from has a mean of 59 for variable X? Please choose the correct response option below. A) Yes. The researcher has enough evidence to reject the null hypothesis. B)No. The researcher does not have enough evidence to reject the null hypothesis. C) The hypothesis test and the 95% confidence interval provide entirely different information. The 95% confidence interval can not be used to know if a hypothesis test would lead to a rejection of the null hypothesis. D)Maybe, but our conclusion would depend upon the magnitude of the standard error. Because the standard error was not explicitly provided, we can not know if the researcher has enough evidence to reject the null hypothesis
B)No. The researcher does not have enough evidence to reject the null hypothesis.
Which of the following statements is true about properly stated null and alternative hypotheses for an experiment? A) The null hypothesis will be about the corresponding samples, while the alternative hypothesis will be about the corresponding populations. B) The null hypothesis will be about the corresponding populations, while the alternative hypothesis will be about the corresponding samples. C) Both the null and alternative hypotheses will be about the corresponding samples. D) Both the null and alternative hypotheses will be about the corresponding populations. E)None of the above.
Both the null and alternative hypotheses will be about the corresponding populations.
According to a "how to stop bullying" website, 15 percent of students reported experiencing bullying within the most recent month. Please treat that "15 percent as a population mean and assume that the standard deviation is 4.5 percent of students. Imagine that Joseph collects data from 225 students at a medium-sized school in low and finds that 11 percent of students reported experiencing bullying. What is his 95 percent confidence interval? A) (2.18. 19.82) B) (6.18. 23.821 C) (10.41, 11.59) D) (14.41. 15.59)
C) (10.41, 11.59)
If a population of scores has a mean of 30 and a standard deviation of 8, what is the standard error of the corresponding distribution of means when the sample size is equal to 100? A) 2.24 B) 0.50 C) 0.80 D) 1.25 E) The answer cannot be computed without also knowing the mean of the sample
C) 0.80
When considering a z score of -1.03 from the standard normal distribution, what percentage of the distribution of scores are at or above z = -1.03? A) 15.15% B) 8.54% C) 84.85% D) 78.81% E) None of the answers above are correct.
C) 84.85%
Imagine that you wish to examine two sample means to decide if you can reject the hypothesis that m1= m2. The sample means are comprised of GPAs (grade point averages) that were collected from the same students on two different occasions (i.e., at the beginning of each student's sophomore year and the beginning of each student's senior year). Which of the following types of tests should you use? A) A z test B) A one-sample t test C) A paired-samples t test D) An independent-samples ttest E) None of the tests listed above could be appropriate.
C) A paired-samples t test
When appropriately conducting an independent-samples t test, which of the following sampling distributions do we use? A) A sampling distribution of the mean B) A sampling distribution of the mean differences C) A sampling distribution of differences between means D) A sampling distribution of the pooled standard error E) None of the above
C) A sampling distribution of differences between means
Which of the following is not an assumption of the z test? A) The dependent variable is measured as a scale variable. B) Participants are randomly selected from the population. C) A two-tailed test is being used. D) The population is normally distributed. E) All of the options listed above are assumptions of the z test.
C) A two-tailed test is being used.
Which of the following is an assumption of the independent-samples t test, but not an assumption of the one-sample t test? A) Random selection from the population or populations of interest B) The dependent variable is measured as a scale variable C) Homogeneity of variance D) All of the answers listed above are assumptions for both types of t tests. E) None of the answers above are assumptions of these t tests.
C) Homogeneity of variance
Which of the following options would increase statistical power for a hypothesis test? (For each option, please assume that only the factor mentioned changes; all other factors remain constant. Please also assume that power is not equal to 0). A) Decrease the alpha level (p level). B) Run a two-tailed test, instead of a one-tailed test (when correctly predicting that the sample mean would be larger than the comparison population mean). C) Increase the distance between the two means that are being examined. D) All of the options above would increase statistical power. E) None of the options above would increase statistical power.
C) Increase the distance between the two means that are being examined.
Which of the following statements is true? A) The alpha level (p level) of a test is always equal to the type ll error rate. B) In the z distribution, 59.10% of scores are above a positive z score of z = 0.23. C) The z test is an example of a parametric test. D) None of the statements above are true.
C) The z test is an example of a parametric test.
In which of the following situations do we use a t distribution, instead of the z distribution, to conduct a hypothesis test comparing two means? A) When we have an extremely large sample size (e.g., greater than 10,000) B) When we do not know the sample size C) When we do not know the population standard deviation D) None of the above. We could legitimately use a z distribution and z test under any of the circumstances described above.
C) When we do not know the population standard deviation
According to Cohen's guidelines for the effect size measure d, which of the following would be an example of a medium effect size? A) d= 0.10 B) d=0.98 C) d= 0.50 D) d= 2.50 E) None of the above
C) d= 0.50
A meta-analysis... A) should only include information from studies published in the most prestigious journals. B) is a useful alternative to the z statistic when working with a positively skewed population distribution. C) involves the use of effect size measurements from multiple studies examining a particular topic. D) None of the options above correctly complete the sentence.
C) involves the use of effect size measurements from multiple studies examining a particular topic.
Cohen's d measures the distance between two means in... A) standard error units. B) z statistics. C) standard deviation units. D) None of the options above correctly complete the sentence.
C) standard deviation units.
Imagine that a researcher correctly conducts a two. tailed, independent-samples t test with an alpha (p level) of 0.05 (5%). The sample sizes for the two groups are 22 and 20. The researcher appropriately rejects the null hypothesis. Which of the following t statistics could not have been obtained when appropriately conducting the t test? A) t=2.135 B) t=.3.378 C) t=2.003 D) t=-2.061 E) t=8.650
C) t=2.003
Grids and ducks are both examples of...
Chart junk
Imagine that a researcher correctly computes a one-sample t statistic for a two-tailed hypothesis test with an alpha level (p level) of 0.05 (5%). The sample size was 16. Based on this information and the rules of hypothesis testing which of the following values for the calculated t statistic would lead the researcher to reject the null hypothesis? A) 2.159 B) 2.326 C) 2.511 D) All of the above E) None of the above
D) All of the above
Imagine that a researcher correctly computes a 95% confidence interval centered on the difference between means for two independent groups. If the 95% confidence interval is [-2.356, 4.819], which of the following would not be a plausible value for the difference between means? A) 0.000 B) 4.457 C) 3.623 D) All of the answers above would be plausible values for the difference between means. E) None of the answers above would be plausible values for the difference between means
D) All of the answers above would be plausible values for the difference between means.
Which of the following options would increase statistical power for a hypothesis test? (For each option, please assume that only the factor mentioned changes; all other factors remain constant. Please also assume that power is not equal to 0). A) Change the alpha level (p level) from 0.05 (5%) to 0.10 (10%). B) Increase the sample size. C) Decrease the magnitude of the population standard deviation. D) All of the options above would increase statistical power. E) None of the options above would increase statistical power.
D) All of the options above would increase statistical power.
Imagine that you wish to examine two sample means to decide if you can reject the hypothesis that u= M2. The sample means are comprised of GPAs (grade point averages) that were collected from different, randomly chosen, students at two different universities. Which of the following types of tests should you use? A) A z test B) A one-sample t test C) A paired-samples t test D) An independent-samples t test E) None of the tests listed above could be appropriate.
D) An independent-samples t test
Imagine that a researcher obtains a mean value of 40 on variable X, and that the corresponding distribution of means has a grand mean (or overall mean) of 44 ( µM = 44). Based on this information, what can we know about the corresponding z statistic? A) The z statistic must be larger than 4.00. B) The z statistic must be fall between the values 0 and 10.00. C) The z statistic must be a positive z statistic. D) The z statistic must be a negative z statistic. E) We can not know any of the statements listed above with out also knowing the value of the standard error.
D) The z statistic must be a negative z statistic.
Consider the following information used for a one- sample t test: N = 31, U = 12, Sm = 3, and M = 15. Based on this information, what is the corresponding 95% confidence interval (when reporting three decimal places)? A) (11.268, 17.913) B) (9.906, 20.094) C) (5.871. 18.1291 D) [8.871, 21.129] E) None of the above
D) [8.871, 21.129]
Consider the following information: Population mean = 8 Population standard deviation = 4 Sample mean = 9 Sample size = 64 Based on this information, what is the corresponding measure of effect size, Cohen's d? A) d= 2.00 B) d=080 C) d=0.65 D) d = 0.25 E) None of the above
D) d = 0.25
Consider the following information used for a one- sample t test: N = 100, M = 30, s = 20, and M = 33. Based on this information, what is the measure of effect size, Cohen's d, rounded to two decimal places? A) d=0.30 B) d=1.50 C) d=0.03 D) d= 0.15 E) d= 0.80
D) d= 0.15
Imagine that a researcher conducts a two-tailed, one-sample t test with a sample size of 36. The obtained t statistic value is 2.66 and the corresponding measure of effect size, Cohen's d, is 1.03. Which of the following would be an accurate and appropriate way of conveying this information, using APA style? A) t(36) = 2.66, p > .05, d = 1.03 B) t=2.66, d = 1.03. p < .05 C) t(36) = 2.66, d = 1.03. p > .05 D) t(35) = 2.66, p < .05. d = 1.03 E) None of the above
D) t(35) = 2.66, p < .05. d = 1.03
If you are correctly told that a distribution is a standard normal distribution, then (without any additional information about that distribution) it is possible to know the exact value of... A) only the mean of that distribution. B) only the standard deviation of that distribution. C) only the mean, the median, and the mode of that distribution. D) the mean, median, mode, variance, and standard deviation of that distribution. E) None of the above
D) the mean, median, mode, variance, and standard deviation of that distribution.
When considering the z scores of positive and negative 1.66 (+/-1.66) from the standard normal distribution, what percentage of the distribution of scores are at least as extreme as those two z scores (i.e., what percentage of the scores are at least as distant from 0 as z = positive and negative 1.66)? A) 7.02% B) 8.54% C) 90.30% D)9.70% E) None of the answers above are correct.
D)9.70%
Consider the following information: Sample size = 100 Population mean (and the mean of the sampling distribution of means) = 30 Standard error = 1 Sample mean = 33 Based on this information, how much power would a corresponding one-tailed z test have to reject the null hypothesis? When answering, please assume that the researcher is using an alpha level (or p level) of 0.05 (5%) with a corresponding critical value of z= 1.65. Additionally, please assume that the researcher is looking in the correct tail of the distribution (i.e., the researcher predicted that the sample mean would be greater than the mean of the comparison population). When calculating your answer, please retain two decimal places at all times. A) 8.85% B) 10.20% C) 93.80% D) 68.52% E) 91.15%
E) 91.15%
What is the critical value for a one-tailed. one-sample † test when the alpha (p level) is 0.05 (5%) and the sample size is 15? When answering, please assume that the researcher is looking in the positive tail of the distribution (i.e., the researcher expects the sample mean to be larger than the population mean). A) 2.132 B) 1.753 C) 1.746 D) 2.603 E) None of the above
E) None of the above
Consider the following means and sample sizes for two independent samples (with the samples being denoted by the subscripts "X" and "y"): Mx = 14, My= 12, nx = 50, ny = 50. If the standard error (Spifference) is 2.5, what is the absolute value of the corresponding t statistic, when rounded to two decimal places? Please use a typical null hypothesis that predicts no differences between the two populations when computing your answer. A) t=8.00 B) t=2.91 C) t= 3.80 D) t=179 E) None of the answers above are correct.
E) None of the answers above are correct.
A 95% confidence interval... A) is an example of a point estimate. B) should always be centered on the population mean. C) provides less information than the corresponding hypothesis test. D) All of the options listed above correctly complete the sentence. E) None of the options listed above correctly complete the sentence.
E) None of the options listed above correctly complete the sentence.
On the basis of a hypothesis test and the accompanying statistics, which of the following decisions could a researcher appropriately make? A) Accept the alternative hypothesis as correct B) Fail to reject the null hypothesis C) Reject the alternative hypothesis D) All of the above E) None of the above
Fail to reject the null hypothesis
Which of the following would be a type Il error? A) Rejecting the null hypothesis when the null hypothesis is actually true. B) Rejecting the null hypothesis when the null hypothesis is actually false. C) Failing to reject the null hypothesis when the null hypothesis is actually true. D) Failing to reject the null hypothesis when the null hypothesis is actually false. E) None of the above.
Failing to reject the null hypothesis when the null hypothesis is actually false.
Is the following statement true or false? As the sample size increases, the corresponding t distribution becomes less similar to the z distribution. True False
False
Is the following statement true or false? Histograms and bar graphs both display data for a single nominal variable and a single scale variable. True False
False
Which of the following would be a continuous variable? A) The number of days per week that a person wakes up before 6:00am B) The number of whole cookies that a person eats from a pack of eight cookies C) Finishing times in a five kilometer (5k) footrace. D) All of the variables above would be continuous variables E) None of the variables would be continuous variables
Finishing times in a five kilometer (5k) footrace.
Imagine that you are correctly told that the outcomes of numerous trials are independent of one another. What does this mean? A) It means that an outcome that hasn't occurred recently must become more likely with each successive trial. B) It means that the outcome of each trial must be unique (i.e., scores cannot be repeated in the data set). C) It means that the outcome of each trial does not depend in any way on the outcomes of other trials. D) It means that the outcomes of the trials must be mutually exclusive of one another. E) None of the above
It means that the outcome of each trial does not depend in any way on the outcomes of other trials.
Which of the following formulae, if used correctly, would produce the correct lower boundary of a 95% confidence interval for a z test?
M lower = -1.96(0m) + M
According to Cohen's guidelines, an effect size of d= 0.50 would be a ________ effect. Please type the correct missing term into the blank above.
Medium
If a distribution with a single peak has a tail that extends to the left, which of the following terms would correctly describe that distribution? A) Multimodal B) Positively skewed C) Negatively skewed D) Symmetric E) None of the above
Negatively skewed
Which of the following types of graphs would be useful for detecting a non-linear relationship between two scale variables? Choose the best answer. A) A histogram B) A Pareto chart C) A pie chart D) All of the options above would be appropriate. E) None of the options above would be appropriate.
None of the options above would be appropriate.
Which of the following would be an example of a ratio variable? A) The flavors of scoops of ice cream (e.g.. vanilla, chocolate, strawberry) B) People's finishing times for the 100 meter dash (measured in seconds) C) People's rankings for their favorite five genres of music D) Air temperatures measured in degrees Fahrenheit E) None of the above
People's finishing times for the 100 meter dash (measured in seconds)
If a distribution with a single peak has a tail that extends to the right, which of the following terms would correctly describe that distribution? A) Bimodal B) Positively skewed C) Negatively skewed D) Symmetric E)None of the above
Positively skewed
Which of the following terms appropriately describe a distribution with a single peak, where the majority of scores are near the left side of the distribution, but the tail of the distribution extends to the right? There may be more than one correct answer. Select all correct answers. Positively skewed Negatively skewed Normal Unimodal
Positively skewed and Unimodal
When appropriately conducting a hypothesis test, which of the following decisions could a researcher appropriately reach upon the basis of that test and the corresponding statistics? Choose all correct answers below. Reject the null hypothesis Reject the alternative hypothesis Fail to reject the null hypothesis Accept the alternative hypothesis
Reject the null hypothesis and Fail to reject the null hypothesis
Which of the following would be a type I error? A) Rejecting the null hypothesis when the null hypothesis is actually true. B) Rejecting the null hypothesis when the null hypothesis is actually false. C) Failing to reject the null hypothesis when the null hypothesis is actually true. D) Failing to reject the null hypothesis when the null hypothesis is actually false. E) None of the above.
Rejecting the null hypothesis when the null hypothesis is actually true.
What is the meaning of the following conditional probability? P( B | A ) Read all answers and choose the best answer below. A) The conditional probability above represents the probability of outcome A occurring, or outcome B occurring, or both occurring. B) The conditional probability above represents the probability of the conjunction (i.e., intersection) of outcomes A and B both occurring. C) The conditional probability above represents the probability of outcome A occurring, given that outcome B has occurred. D) The conditional probability above represents the probability of outcome B occurring, given that outcome A has occurred. E) None of the answers listed above are correct.
The conditional probability above represents the probability of outcome B occurring, given that outcome A has occurred.
Which of the following "lies" involves the assumption that a pattern in the data (e.g., the values shown for variables) will continue beyond the range of the data? A) The biased scale lie B) The extrapolation lie C) The interpolation lie E) None of the above
The extrapolation lie
Which of the following would be an example of a nominal variable? A) The flavors of scoops of ice cream (e.g., vanilla, chocolate, strawberry) B) People's rankings for their favorite five genres of music C) People's heights measured in centimeters D) Air temperatures measured in degrees Fahrenheit E) None of the above
The flavors of scoops of ice cream (e.g., vanilla, chocolate, strawberry)
Which of the following are measures of central tendency? Choose all correct answers. The mean (also called the arithmetic mean) The mode The variance The standard deviation The median The range
The mean, mode, median
Which of the following options represents the midpoint of a distribution of scores, so that half of the scores fall at or above the midpoint, and half of the scores fall at or below the midpoint when the scores are arranged in ascending order? (Your answer should work for both normal and skewed distributions). A) The mean B) The median C) The mode D) The range E) The variance
The median
Which of the following would be a discrete variable? A) Finishing times in a five-kilometer (5K) foot race B) The distance driven each day by Columbus residents C) The number of days per week that students go to sleep after 11:00pm D) All of the variables above would be discrete variables E) None of the variables would be discrete variables
The number of days per week that students go to sleep after 11:00pm
Imagine that a researcher appropriately rejects a null hypothesis (with that null hypothesis stating that there is no difference between two means in the population). What is an appropriate interpretation for the rejection of the null hypothesis on the basis of the hypothesis test and the corresponding statistics? A) The observed differences between means were due to sampling error. B) The probability of obtaining the observed difference between means (or an even more extreme difference) is very unlikely. C) The probability of obtaining the observed difference between means (or an even more extreme difference) is very unlikely, given that the null hypothesis is false. D) The probability of obtaining the observed difference between means (or an even more extreme difference) is very unlikely, given that the null hypothesis is true. E) None of the above.
The probability of obtaining the observed difference between means (or an even more extreme difference) is very unlikely, given that the null hypothesis is true.
If a null hypothesis really is false, which type(s) of errors) could a researcher make (in regards to that hypothesis. with a specific hypothesis test)? A) The researcher could make only a type I error. B) The researcher could make only a type Il error. C) The researcher could make both a type I error and a Type Il error. D) If the null hypothesis really is false, the researcher can't make any errors. '
The researcher could make only a type Il error.
Imagine that you are told that the probabilities of certain outcomes are independent of one another. What does this mean? Read all options below and choose the best answer. A) The statement means that a particular outcome becomes more likely if that outcome has not occurred on any recent trials. B) The statement means that the outcome of each trial must be unique (i.e., scores cannot be repeated in the data set). C) The statement means that the outcome of each trial does not depend in any way on the outcomes of other trials. D) The statement means that the outcomes being considered must be mutually exclusive of one another. E) None of the statements above appropriately describe independent outcomes.
The statement means that the outcome of each trial does not depend in any way on the outcomes of other trials.
Is the following statement true or false? All other things being equal, outliers tend to have a greater effect on the value of the mean, as compared to the value of the median. True False
True
A list of properties is below. Please select each property that applies to a normal distribution. You may need to select more than one property to correctly answer this question. Unimodal Positively skewed Negatively skewed Bell-shaped Symmetric
Unimodal, bell-shaped, symmetric
After reading the following scenario, please choose the response that most accurately completes the last sentence. Imagine that an instructor provides a survey to all of the students enrolled in his statistics class in which he asks them whether they plan to go to graduate school. All students in that class complete the survey. The instructor is only interested in learning how many students in that particular class plan to go to graduate school and he will not use the data that the students provide for any other purpose. In this particular case, the students who completed the survey ___________. A) are a population B) are a sample C) provide the instructor with an inferential statistic through their responses D)None of the options provided can accurately complete the sentence.
are a population
Moiré vibrations are an example of... A) population parameters. B) grids C) statistics. D) chart junk. E) None of the above.
chart junk
In a truly normal distribution, the mean is always equal to... A) the median. B) 1. C) the standard deviation D) the variance. E) None of the above
the median.
If a type II error occurs, this means that... Read all options below and choose the response that best completes the sentence fragment. A) the researcher rejected the null hypothesis when the null hypothesis was correct B) the researcher failed to reject the null hypothesis when the null hypothesis was false. C) the researcher must have made a mistake when running or designing the study. D) the researcher rejected the null hypothesis when the null hypothesis really was false. E) None of the answers above correctly complete the sentence.
the researcher failed to reject the null hypothesis when the null hypothesis was false.
Imagine that a researcher collects data from a random sample of 300 undergraduate students with the goal of learning more about all 7000 undergraduate students at a particular university. In order to do so, the researcher... A) should use a convenience sample to maximize external validity. B) would calculate inferential statistics. C) would calculate only descriptive statistics. D) should use a volunteer sample to maximize external validity. E) would do none of the things listed above.
would calculate inferential statistics.
To learn something about a larger population from a sample, a researcher... A) would calculate inferential statistics. B) would calculate only descriptive statistics. C) should use a convenience sample to maximize external validity. D) should use a volunteer sample to maximize external validity. E) would do none of the things listed above.
would calculate inferential statistics.
