Psych Stats: Learning Curve Questions
Which of the following was NOT discussed in your text as an important component of conducting a meta-analysis?
Collect new data to fill in gaps from previous studies
What is the primary advantage of a dot plot over other frequency histograms and frequency polygons?
Dot plots allow us to see every single data point.
When creating a dot plot, how are multiple data points for a single score displayed?
Multiple dots, representing each data point, are placed on top of one another.
The measure of effect size calculated for ANOVA is:
R2
Which of the following is the correct formula for calculating R2 in a one-way between-groups ANOVA?
SSbetween/SStotal
Which of the following are three components that would completely specify a confidence interval?
estimate of the population parameter, the confidence level, and the margin of error
The term "new statistics" does NOT include:
hypothesis testing.
Compared to a Tukey's HSD test, using a Bonferroni test increases the risk of:
a Type II error
Partial correlation investigates the correlation between two variables after effectively _____ the effect of a third variable.
removing
The formula of standard error σM is: σ/√N. What does σ represent?
standard deviation
After conducting a one-way within-groups ANOVA, if the F test statistic is greater than _____, the researcher should reject the null hypothesis.
the cutoff value
The difference in calculating the effect size in a single-sample t test and a z test is that the effect size is calculated using the:
population standard deviation instead of the population standard error.
The p level of a study determines the:
probability used to determine the critical value, or cutoffs, in hypothesis testing
In a study designed to test the results of cramming versus spaced practice, the researcher finds that students who crammed scored an average of 72 on the exam while students who spaced out their practice scored an average of 78 on the exam. If the value of sdifference is 2.5, what is the value of t?
-2.4
In a one-way, repeated-measures ANOVA, SSBetween = 50, SStotal= 300, and SSSubjects = 25. What is the value of R2?
0.18
In a situation in which we have a weak prior belief, we will _____ findings that are not consistent with the belief
be more confident in
A measure is said to be valid if:
it measures what it is supposed to measure.
An eager graduate student has just completed a within-groups ANOVA that had three levels of the independent variable and 15 participants. He used a p level of 0.05 and calculated a between-groups F statistic of 3.26. Based on this result, which of the following is a reasonable next step?
The effect size, R2 and/or a confidence interval should be calculated.
Why is it preferable to use a range of plausible variables rather than just reporting a single number?
The interval estimate tends to be more accurate.
Based on the statement, t(25) = 5.75, p < 0.05, what would you conclude?
The null hypothesis was rejected at an alpha level of 0.05.
How are sample size and degrees of freedom related in a single-sample t test?
They are directly related—as sample size increases, so do degrees of freedom.
Why do we divide by N - 1 rather than by N when estimating a population standard deviation from the sample standard deviation?
We allow the error of our estimate (the standard deviation) to be larger by dividing the sum of squares by a smaller number because the sample standard deviation is likely to be an imprecise estimate.
Dot plots make it easy to compare two groups by:
placing the plot for one group directly above the plot for the second group.
Consider a study using a between-groups design with between-groups df = 2 and within-groups df = 42. Given a p level of 0.05, the researcher should:
reject the null hypothesis if F > 3.23.
As sample size increases:
standard error increases.
Which of the following provides a measure of practical importance?
the measure of effect size d
Calculation of the Bonferroni test involves dividing:
the p level by the number of comparisons.
What is the research hypothesis when testing for significance using the Pearson correlation coefficient?
ρ ≠ 0
An estimate of the population variance based on the differences among group means is:
between-groups variance.
An advantage of the matched groups research design is that it:
has more statistical power than the between-groups design with random assignment.
Populations are described as _____ if the populations do not have approximately the same variance
heteroscedastic
It is known that the population mean for the verbal section of the SAT is 500 with a standard deviation of 100. In 2006, a sample of 400 students taking the SAT whose family income was between $70,000 and $80,000, had a verbal SAT score of 513. The 95 percent confidence interval for this group is:
503.20, 522.80
Alex conducts a Tukey HSD test based on the SAT scores of his students. It is found that the mean sum of square of squares within is 520 and sample size is 50. Calculate standard error.
3.22
Asia calculates her degrees of freedom values as dfbetween = 2 and dfWithin = 16. Assuming an alpha level of 0.05, what is the critical value of F?
3.63
Consider this confidence interval interpretation: Sharon is confident the mean sodium content for all beef hot dogs is between 353.2 and 449.1 mg. What needs to be done to fix this statement?
The confidence level is either not reported or not reported correctly.
The results of an independent-samples t test are reported in a journal as: t(14) = 1.14, p > 0.05. What decision was made?
Fail to reject the null hypothesis.
Financial aid offices are interested in how much a student might reasonably be able to earn when figuring out financial aid packages. A simple random sample of students at one university in southern Georgia was interviewed about how much money they earn each month. The resulting 95 percent confidence interval was ($150.75, $223.74) for those with part-time jobs. What should this confidence interval contain?
This confidence interval should contain the true mean monthly earnings for all students with part-time jobs at that university.
Which of the following is a reason that researchers are increasing the use of effect sizes and confidence intervals when reporting their results?
Hypothesis testing alone can lead to inaccurate interpretations.
There is a different F distribution for every:
combination of sample size and number of samples.
In addition to the results of hypothesis tests, the APA recommends that researchers also report
confidence intervals and effect sizes.
By typically including unpublished research with null findings, the effect size of meta-analytic studies is often:
lower than those calculated in individual studies.
When conducting a paired-samples t test, because the null hypothesis posits no difference between the populations, the comparison distribution is a distribution of:
mean differences with a mean of 0
Tara wanted to assess the reliability of her measure of happiness so she had a group of introductory psychology students complete the measure of happiness two times and then compared the scores, calculating a correlation coefficient. What method did Tara use to assess reliability?
test-retest
Statistical power is related to:
the probability of not making a Type II error.
The major difference between the formula for the t statistic and the z statistic is:
the use of standard error instead of standard deviation in the denominator
A disadvantage of the matched groups design is that:
we may neglect to match on some of the important variables.
Imagine a presidential election in which no polling data has been collected. In evaluating the results of the first poll, you have a:
weak prior belief
Hypothesis testing tells us:
what are significant results, but does not indicate anything about the importance of those results.
Under what circumstance would a dot plot not be a good graphical option?
when the sample size is very large
Marlene predicts that Group 1 will outperform Group 2 on a test. In analyzing her data, she finds that the total degrees of freedom value is 15. Assuming an alpha level of 0.05, what is/are the critical value(s)?
+1.753
The type of statistical thinking that evaluates each new piece of information in terms of a growing set of prior beliefs is called:
Bayesian analysis.
Which of the statements is true regarding correlation?
Correlations only provide clues to causality.
What technique was discussed in your text to minimize order effects?
Counterbalance the order of the levels of the independent variable
F is obtained by dividing _____ by _____.
MSbetween; MSwithin
For which of the following intervals is it MOST likely that the samples come from populations that are identical?
[-2.5, 5.2]
A sample statistics that provide a range of plausible values for the population parameter is:
interval estimate
By convention, an R2 value of 0.16 would be considered:
large
A ______ is defined as just one number used as an estimate of the population parameter.
point estimate
A(n) _____ is a summary statistic from a sample that is just one number used as an estimate of the population parameter.
point estimate
_____ is a measure of effect size that can be used with one-way between-groups ANOVA.
r2
Statistical power is a measure of a researcher's ability to _____ the null hypothesis when it is false
reject
After conducting a paired-samples t test, if the test statistic is less than the lower cutoff or greater than the upper cutoff, the researcher should:
reject the null hypothesis
Which of the following is false about t distribution?
We gain more confidence when z distributions begin to merge with the t distribution
Given a sample mean difference of 23, a standard error of 4.2, and a critical t value of 2.262, what are the values for the confidence interval?
[13.5, 32.5]
Sarah calculates Cohen's d for a paired-samples t test. The value is d = 0.92. By convention, this is a _____ effect
large
In a dot plot, each _____ is represented by a single dot.
score in the sample
When developing a new scale or measure that will be used to make decisions about individuals, the reliability should be at least _____.
0.90
After calculating a paired-samples t test, given a two-tailed test, a p level of 0.10, and 12 degrees of freedom, the critical values for t have an absolute value of: (Answer using 3 decimal places.
1.783
A researcher has set up a two-tailed test for a certain experiment. They have set the cutoff at 5%. What percentage of cases in each tail in the distribution rejects the null hypothesis?
2.5 percent
Suppose you calculate a t test statistic based on a random sample of 21 individuals. What is the critical value t such that the distribution has probability 0.01 to the right of t?
2.528
Consider a study using a one-way within-groups design with three participants exposed to each of four conditions. Given a p level of 0.05, the researcher should fail to reject the null hypothesis if F < _____.
4.76
If the student newspaper reported "51 percent of students support the move to 4-day-a-week classes with a margin of error of 4 percent," which of the following would represent the interval estimate?
47 percent to 55 percent
A researcher reports that dfbetween = 4 and dfwithin = 20. How many participants were in this study?
6
A researcher wondered if his new relaxation training method would result in better than average results in helping people to stop smoking. He recorded the average number of cigarettes smoked for his 25 patients six months after undergoing the relaxation training program and compared this to the national average for all smoking cessation programs. Which of the following represents in the null hypothesis for this scenario?
H0: μ1 = μ2
Dr. Faison conducts a study that reveals a positive correlation between annual salary and annual amount of seafood consumed. Based on this information, which statement is false?
Individuals who eat a lot of seafood tend to have lower salaries than those who eat little seafood.
When calculating a confidence interval, you find that 0 occurs within your interval. What does this indicate?
It is plausible that the two distributions are identical
Mehl (2007) published in the journal Science the results of an extensive study of 396 men and women, comparing the number of words uttered per day by each sex. Assuming a two-tailed test, which of the following would be the null hypothesis?
Men and women do not differ in the number of words uttered
Carra conducts a study and the resulting effect size is small. She decides to replicate the study with a larger sample size. All else being equal, what should she expect to happen to the effect size?
The effect size will stay the same.
Roman wanted to assess the internal consistency of his measure of happiness so he measured reliability estimates by comparing items within his test. He reported a reliability estimate of +0.75. What measure of reliability is Roman using?
coefficient alpha
Within-groups variance is an estimate of the population variance based on the:
differences within each of the sample distributions.
The sign of the correlation coefficient indicates the _____ of the correlation, positive or negative.
direction
The t statistic indicates the:
distance of a sample mean from a population mean in terms of the standard error.
The condition for the ANOVA inference that all populations must have the same variance is considered satisfied if the:
largest sample variance is no more than twice as large as the smallest one
Financial aid offices are interested in how much a student might reasonably be able to earn when figuring out financial aid packages. A simple random sample of students at one university in southern Georgia was interviewed about how much money they earn each month. The resulting 95 percent confidence interval was ($150.75, $223.74) for those with part-time jobs. What sample estimate was the confidence interval based upon?
mean monthly earnings for students sampled with part-time jobs at that university
Which of the following would increase statistical power?
using a sample size of 50 instead of 20
There is evidence of _____ when a scale correlates with other scales that measure the same thing
validity
Failing to randomly select the individuals that participate in a study _____ of the paired-samples t test, but it does not preclude use of this test because the paired-samples t test is a robust hypothesis test.
violates one of the assumptions
As sample size gets larger, the t distributions get:
wider
A _____-groups ANOVA is a hypothesis test in which there are more than two samples and each sample is composed of the same participants.
within
Which of the following designs would result in the greatest statistical power?
within-groups (repeated measures)
Which of the following designs would be most susceptible to order effects?
within-groups, before and after design
Amber has taken a mathematics exam, and she wants to calculate an 80 percent confidence interval to represent the scores within her friend group. What are the z statistics that fall at each line marking the middle 80 percent of scores in the distribution?
+/− 1.28
After calculating a paired-samples t test, given a one-tailed test, a p level of 0.05, and 15 degrees of freedom, the critical values for t have an absolute value of:
1.753
When computing a 95 percent confidence interval, we would use z =_____. (Answer using 2 decimal places.)
1.96
Consider a study comparing the effects of three different drugs on memory for words in a recall memory test. The scores, numbers of words remembered, are provided for six individuals tested after taking each of the three drugs (but in different orders). Red Drug: 7, 9, 8, 9, 7, and 8 White Drug: 5, 7, 6, 8, 9, and 7 Blue Drug: 7, 7, 5, 5, 5, and 6 The dfbetween for the one-way within-groups ANOVA is _____.
2
In a within-groups ANOVA MSbetween = 10, MSwithin = 5, dfbetween = 22, and dfwithin = 35. What is the value of F?
2
Which of the following statements is true?
A post hoc test will let us know which specific pairs of means are different from one another.
In the first step to calculating a confidence interval, we draw a distribution with the _____ mean at its center.
sample
A study by Bettmann (2007) published in the Journal of the American Psychoanalytic Association assessed whether the attachment relationships between adolescents and their parents change as a result of a residential wilderness treatment experience for the adolescents. Participants completed the Adolescent Attachment Questionnaire at the start and at the end of the wilderness program. Which of the following would be the null hypothesis for this study?
H0: μ = μ
Each end of the confidence interval should be exactly the same distance from the:
sample mean
The df used to determine the critical values for a paired-samples t test is:
N - 1
Other things being equal, which of the following scenarios would result in the greatest power?
N = 1000; alpha 5 percent; one-tailed test
As sample size gets larger, the t distributions get:
Narrower
When calculating the confidence interval for a single-sample t-test, the interval is centered around the:
sample mean
A researcher is interested in the effects of humor on memory and randomly assigns 16 participants to either the humor group or the no-humor group. The humor group reads humorous sentences and the no-humor group reads nonhumorous sentences. On a later memory test, the researcher finds that in terms of the direction of the means, the humor group had better memory than the no-humor group, but this effect was not significant. What might you recommend that this researcher do?
She can increase her sample size to increase her power to detect the effect because the effect looks as though it is barely missing significance, and her sample size is fairly small
The _____ test is a widely used post hoc test following one-way between-groups ANOVA that determines the differences between means in terms of standard error.
Tukey HSD
Which of the following statements is false?
When calculating a confidence interval using a z distribution the population mean is used in the calculations.
The purpose of effect size in independent-samples t test is to have a measure that is not influenced by the:
sample size
Partial correlation:
allows the researcher to control for the influence of one or more variables.
In a re-analysis of published studies, Twenge and Im (2007) found that for the time period of 1958 to 2001, the need for social approval of people in the United States was negatively correlated with the U.S. violent crime rate during that same period (the correlation coefficient was -0.31). This means that:
as the need for social approval went up, the number of violent crimes decreased.
Hout, Duncan, and Sobel (1987) reported on the relative sexual satisfaction of married couples. They asked each husband and wife of 91 married couples to rate the degree to which they agreed with the statement "Sex is fun for me and my partner." What statistical test would we use to determine whether there is, on average, a difference in the sexual satisfaction of husbands and wives?
paired-samples t test
Which of the following experimental designs gains the most benefit from counterbalancing?
paired-samples t tests
Samantha compares her class's average score on a standardized statistics exam (M = 43) to the known national population mean for the same exam (μM = 44). The standard error based on her class (N = 36) is 1.2. If she wants to conduct a t test, which of the following is the correct formula?
(43 - 44)/1.2
Identify the formula for the single-sample t test.
(M - μM)/sM
A professor wants to know whether critical-thinking skills change as a student progresses through college. He compares critical-thinking skills for a group of 100 students at three time points: during the students' first semester, fifth semester, and eighth semester. Students in their first semester have an average score of 56.5, students in their fifth semester have an average score of 58, and students in their eighth semester have an average score of 60. If the value of the standard error is 3, what is the HSD value for the comparison between the first and fifth semesters?
-0.5
Kelvin has collected data using a within-groups design to investigate the effect of different video games on dopamine release in the striatal cortex. He recruited 8 college students and had them each play four different video games while he monitored their dopamine levels. The mean increase in dopamine levels for the first game was 7 percent, 2 percent for the second game, 11 percent for the third game, and for the final game, 15 percent. Further calculations show that the standard error is 2.03. What is the Tukey HSD value for the comparison between the first and third games? (For the purposes of these calculations treat the percentages as integer values, not decimals.)
-1.97
Suppose you calculate a t test statistic based on a random sample of 27 individuals. The critical value such that the distribution has probability 0.01 to the left of it is t = _____. (Answer using 3 decimal places.)
-2.479
Richard is calculating the variance of the distribution of the differences between means (s2difference). The pooled variance for his data is 0.52. He has 5 participants in one group and 6 in the other. What is the value of s2difference?
0.19
When developing a new scale or measure, the reliability should be at least _____. If the scale will be used to make decisions about individuals, the reliability should be at least _____.
0.80; 0.90
A researcher conducts a one-way between-groups ANOVA test. It is found that the between-groups mean square is 20, and the within-groups mean square is 7.8. What is the value of F?
2.56
Consider a study testing the hypothesis that, on average, individuals will remember more words in a recall memory test when they are given a new cognitive enhancement drug than when they are given a placebo. The scores, numbers of words remembered, are provided for five individuals tested in both conditions. Drug condition: 7, 9, 8, 9, and 8 Placebo condition: 5, 7, 6, 8, and 9 Using a two-tailed test and p level of 0.05, the absolute value of the critical values for t is _____. (Answer using 3 decimal places.)
2.776
Consider a study using a within-groups design with between-groups df = 3 and within-groups df = 51. Given a p level of 0.05, the researcher should reject the null hypothesis if F > _____.
2.79
After calculating a paired-samples t test, given a two-tailed test, a p level of 0.01, and a dftotal 18, the critical values for t have an absolute value of:
2.879
Shamika conducts a study comparing the performance of individuals in three different statistics classes taking the same quiz. The scores, out of 100, are provided for individuals in each group. Class 1: 87, 78, 87, 85, 93, 98, 83, 82, and 73 Class 2: 87, 86, 92, 90, 90, 91, 89, 78, and 76 Class 3: 87, 78, 92, 85, 90, 98, 89, 82, and 76 The MSbetween, which is necessary to complete the final calculation of F, is:
5.444
Consumers are asked to estimate the maximum amount of money that they would consider paying for various items of clothing. The standard error is calculated as 5.67, and the mean prices for each item are as follows: Jeans $100, Sweater $120, and Shoes $85. What is the Tukey HSD value for the comparison between the mean for sweater and the mean for shoes?
6.17
Hout, Duncan, and Sobel (1987) reported on the relative sexual satisfaction of married couples. They asked each husband and wife of 91 married couples to rate the degree to which they agreed with the statement "Sex is fun for me and my partner." Assume that the critical values for the accompanying test are ±2.00. Which of the following statements would be true?
A calculated t value larger than +2.00 or smaller than -2.00 would indicate that we should reject the null hypothesis.
_____ approach statistical analysis in a different way than traditional hypothesis testing
Bayesian statistics
If our critical value for t is 2.015 and our calculated test statistic is 2.012, what should we conclude?
Fail to reject the null hypothesis
Carra conducts a study and the resulting effect size is small. Since there were some unexpected problems the first time, she decides to replicate the study and, this time, there is a larger difference between means. All else being equal, what should she expect to happen to the effect size?
The effect size will increase.
A researcher is interested in comparing the effectiveness of two antibiotic drugs. She is unable to use a within-groups design, so she decides to match her participants. Which would be the BEST variable on which to match the participants?
The number of other drugs that the participant takes is an important variable of interest.
A researcher wondered if his new relaxation training method would result in better than average results in helping people to stop smoking. He recorded the average number of cigarettes smoked for his 25 patients six months after undergoing the relaxation training program and compared this to the national average for all smoking cessation programs. Imagine the results of his test are as follows: t(24) = 1.24, p > 0.05. Which of the statements below would logically follow?
The relaxation training program did not result in reduced smoking rates.
Suppose that a graduate student collects data for a study designed to test the hypothesis that individuals retain more information if they study while listening to classical music. The student uses a paired-samples design and finds that, on average, participants remembered 3.1 more items when listening to music compared to studying in silence. If the sum of squares for the difference data is 281 and there were 9 participants in the study, what is the 95% confidence interval for the population mean difference?
[-1.46, 7.66]
The Bonferroni test is:
a post-hoc test and is more conservative than the Tukey's HSD test.
A confidence interval is:
an interval estimate that would include the population mean a certain percentage of the time if we sampled from the same population repeatedly.
In a re-analysis of published studies, Twenge and Im (2007) found that for the time period of 1958 to 2001, the need for social approval of people in the United States was negatively correlated with the U.S. divorce rate during that same period (the correlation coefficient was -0.38). This means that:
as the need for social approval increased, divorce rates decreased.
Suppose a teacher would like to know which of two test-taking strategies—multiple choice questions first or short answer/essay questions first—results in greater exam scores and so she decides to split one of her classes into two groups to be given exams by her assistants. To ensure that all of the bright students don't end up in the same group, she ranks the students based on their previous exam score, puts them in pairs (e.g., the two highest exam scores, the next two and so on), and then assigns one member of each pair to the multiple-choice questions group and one to the short answer/essay questions group. What type of research design is this teacher using?
between-groups design with matching
Dr. Evans conducts an experiment that includes thousands of participants and reveals a statistically significant result. Knowing that it is not surprising for studies with large sample sizes to produce statistically significant results, Dr. Evans should _____ to reflect the importance of her findings in a way that is not affected by sample size.
calculate a measure of effect size
Which of the answer choices describes how often confidence intervals will capture the true parameter value in repeated sampling?
confidence level
Researchers interview a group of women with knee pain awaiting knee replacement surgery. They also interview a group of women from the same geographical area with no knee pain. These researchers report that wearing high-heeled shoes causes the knee pain that requires surgery. The women's weight might also be a contributing factor to knee pain. Because we have no clear information on weights of these women, this would be a _____ variable.
confounding
Your instructor decides to test the effectiveness of two different lecture techniques—multimedia vs. discussion—for her two sections of statistics. In one section she uses the multimedia technique during the first half of the semester and discussion for the second half; the opposite order is used for the second section. What is the name of the technique your instructor used to avoid confounding due to order effects?
counterbalancing
The effect size is based on the spread of the distribution of individual scores, rather than the:
distribution of needs
Consider a study comparing the performance of individuals on the first quiz in each of two classes taken in the first term of their freshman year. The scores, out of 100, are provided for nine individuals in both classes. Class 1: 87, 78, 87, 85, 93, 98, 83, 82, and 73 Class 2: 87, 86, 92, 90, 90, 91, 89, 78, and 76 Based on the given APA formats for the above study, t(8) = 0.84, p > 0.05, one should:
fail to reject the null hypothesis
Roselle conducts a study comparing the performance of individuals on the first quiz in each of two classes taken in the first term of their freshman year. The scores, out of 100, are provided for nine individuals in both classes. Class 1: 87, 78, 87, 85, 93, 98, 83, 82, and 73 Class 2: 87, 86, 92, 90, 90, 91, 89, 78, and 76 Given a two-tailed test and a p level of 0.05, based on the value of the t statistic, Roselle should:
fail to reject the null hypothesis
Consider a study using a between-groups design with 45 participants-15 participants in 3 groups. Given a p level of 0.05, the researcher should:
fail to reject the null hypothesis if F < 3.23.
Consider a study using a one-way within-groups design with between-groups df = 3 and within-groups df = 42. Given a p level of 0.01, the researcher should:
fail to reject the null hypothesis if F < 4.31.
If you calculate an F statistic and find that it is smaller than your critical value, you would:
fail to reject the null hypothesis.
The difference between the denominator of the z test and that of the single sample t test is that:
in the z test we divide by the actual population standard error (σM), but in a t test we divide by the estimated standard error (sM).
As the degrees of freedom _____, the t curve approaches the standard normal curve.
increase
Other things being equal, a larger difference between sample means will _____ effect size.
increase
A professor took a sample of 200 students who attended CRCT exam to examine the effect of three different teaching methods. It is found that the between-groups sum of squares and total sum of squares are 120 and 850, respectively. The effect size would be considered:
large
Consider a study comparing the effects of three different drugs on memory for words in a recall memory test. The scores, numbers of words remembered, are provided for six individuals tested after taking each of the three drugs (but in different orders). Red Drug: 7, 9, 8, 9, 7, and 8 White Drug: 5, 7, 6, 8, 9, and 7 Blue Drug: 7, 7, 5, 5, 5, and 6 According to conventions for R2, the effect size for this study is:
large
Dr. Riesling conducts a study examining the relation between grade point average (GPA) and number of hours of studying per week with 30 participants. Using a two-tailed test, with a p level of 0.05, Dr. Riesling should fail to reject the null hypothesis if the absolute value of r is:
less than 0.361.
The relationship between the number of televisions per capita (X) and average life expectancy of people (Y) in various countries around the world has a strong positive correlation. Because of this, we should:
look for other potential reasons to explain the relationship
Beth is able to reject the null hypothesis and calculates an effect size of 0.55. Using the conventions for Cohen's d, what is the size of her effect?
medium
Shawna calculates an effect size, R2, after rejecting the null hypothesis for her one-way within-groups ANOVA. The value of R2 is 0.07. Based on the conventions, how large is this effect?
medium
A measure of the degree of association between two variables after statistically removing the association of a third variable is called:
partial correlation
For Cohen's d, we replace the denominator of the t statistic with _____ instead of standard error, sdifference.
pooled standard deviation, spooled
Which of the following values is NOT needed in calculating the 95 percent confidence interval for the z statistic?
population mean
A point estimate is a summary statistic from a sample that is just one number used as an estimate of the:
population parameter
In order to conduct inference on a population mean, the data used must be the result of a:
random sample
Consider a study using a one-way within-groups design with three participants exposed to each of four conditions. Given a p level of 0.05, the researcher should _____ the null hypothesis if F is greater 4.76
reject
A confidence interval for the paired-samples t test is centered around the _____ mean of the difference scores
sample
Standard error is calculated by dividing the:
sample standard deviation by the square root of N.
Statistical power is a measure of a researcher's ability to reject the null hypothesis when it:
should be rejected.
A newspaper article reported that the typical American family spent an average of $81 for Halloween candy and costumes last year. A sample of N = 16 families this year reported spending a mean of M = $85, with s = $20. What statistical test would we use to determine whether these data indicate a significant change in holiday spending?
single-sample t test
If the standard deviation for a population, as estimated from a sample, is s = 5.16, then the standard error for a sample size of N = 20 is:
sm = 1.15
The difference in the calculation of standard error for the z and t statistics results in the t statistic being:
smaller than the z statistic
Imagine a presidential election in which 100 different polls predict that Candidate 1 will win, while only 2 polls predict that Candidate 2 will win. In this situation, you have a _____ that you can use to evaluate new information.
strong prior belief
Which distribution has a greater spread?
t
Within-groups variance reflects:
the amount of difference between means that we would expect to occur by chance alone.
In order to decide whether or not to reject the null hypothesis based on the results of an independent-samples t test, we compare the test statistic to:
the critical values
When calculating a confidence interval for the z statistic:
the sample mean falls in the middle of the interval
The null hypothesis states that:
there is no difference between populations or that the difference is in the opposite direction than anticipated.
Partial correlation allows for the control of _____ variables.
third
For the same number of observations, degrees of freedom will always be _____ for an independent-samples t test as compared to a paired-samples t test.
twice as large
Cherise has been given data from a study where the participants were grouped by socioeconomic status (high, moderate, low), and by high school type (home, public, private, or parochial), and data was collected on the participants' GPAs after their freshman year of college. Based on this experimental design, Cherise should perform a _____-way between-groups ANOVA.
two
Cheyenne has been given data from a study where the participants were grouped by socioeconomic status (high, moderate, low), and by high school type (home, public, private, or parochial), and data was collected on the participants' GPAs after their freshman year of college. Based on this experimental design, what type of ANOVA should Cheyenne perform?
two-way between-groups
The t distributions are more versatile than the z distribution because:
we can use them when we compare two samples.
One difference between the calculation for R2 for a one-way between-groups ANOVA and the R2 calculation for a one-way within-groups ANOVA is the calculation for the:
within-groups ANOVA removes the variability caused by differences among participants.
The F statistic increases when:
within-groups variance decreases and between-groups variance increases
In a study there are 10 participants in Group 1 and 12 participants in Group 2. Assuming a two-tailed test with an alpha level of 0.01, what are the critical values?
±2.845
What is the null hypothesis when testing for significance using the Pearson correlation coefficient?
ρ = 0
Carlos conducts a study comparing the performance of individuals on the first quiz in each of two classes taken in the first term of their freshman year. The scores, out of 100, are provided for nine individuals in both classes. Class 1: 87, 78, 87, 85, 93, 98, 83, 82, and 73 Class 2: 87, 86, 92, 90, 90, 91, 89, 78, and 76 The value for t is _____. (Answer using 2 decimal places.)
.84
Riley conducts a study comparing the performance of individuals on the first quiz in each of two classes taken in the first term of their freshman year. The scores, out of 100, are provided for nine individuals in both classes. Class 1: 87, 78, 87, 85, 93, 98, 83, 82, and 73 Class 2: 87, 86, 92, 90, 90, 91, 89, 78, and 76 Given s = 5.175, Cohen's d is _____. (Answer using 2 decimal places.)
0.28
Devon conducts a study comparing the performance of individuals on the first quiz in each of two classes taken in the first term of their freshman year. The scores, out of 100, are provided for nine individuals in both classes. Class 1: 87, 78, 87, 85, 93, 98, 83, 82, and 73 Class 2: 87, 86, 92, 90, 90, 91, 89, 78, and 76 The standard error, sM, needed to complete the final calculation of the paired-samples t test is _____. (Answer using 2 decimal places.)
1.73
Given a population mean of 7.2, a sample mean of 8.7, and standard error of 0.50, calculate the single sample t value.
3.00
Ian has a sample of 36 rats in his study. If he conducts a single-sample t-test, what is the value of the degrees of freedom?
35
When Cohen's d is large (based on Cohen's conventions), the amount of overlap between the two distributions being compared is:
53 percent
A researcher wondered if his new relaxation training method would result in better than average results in helping people to stop smoking. He recorded the average number of cigarettes smoked for his 25 patients six months after undergoing the relaxation training program and compared this to the national average for all smoking cessation programs. Which of the following represents in the null hypothesis for this scenario?
Patients undergoing the relaxation training method will smoke the same number of cigarettes, on average, as compared to the national average for smoking cessation programs.
Cohen's d is:
a measure of effect size that assesses the difference between two means in terms of standard deviation.
File drawer analysis is
an analysis of the number of studies with null results that would have to exist in order for a mean effect size to no longer be significant.
File drawer analysis is:
an analysis of the number of studies with null results that would have to exist in order for a mean effect size to no longer be significant.
Which of the following components are included in the new statistics?
an effect size, the confidence interval, and the meta-analysis
The z statistics for the lower and upper ends of the 95 percent confidence interval:
are always the same.
The _____ is a graph that displays all the data points in a sample, with the range of scores along the x-axis and a dot for each data point above the appropriate value.
dot plot
The only difference in the t statistic and the z statistic is:
in the denominator.
As the size of the effect of the independent variable increases, power tends to:
increase
Consider a study testing the hypothesis that, on average, individuals will remember more words in a recall memory test when they are given a new cognitive enhancement drug than when they are given a placebo. The scores, numbers of words remembered, are provided for five individuals tested in both conditions. Drug condition: 7, 9, 8, 9, and 8 Placebo condition: 5, 7, 6, 8, and 9 Given a two-tailed test and a p level of 0.05, based on the 95% confidence interval, the researcher can conclude that:
it is plausible that there is no difference between the means.
The larger the effect size the:
less two distributions overlap.
Statistical power can be defined as the probability:
of correctly rejecting the null hypothesis.
(Mdifference - 0) / sM is the formula for a(n):
paired-samples t test
Hermione conducts a study comparing the performance of individuals on the first quiz in each of two classes taken in the first term of their freshman year. The scores, out of 100, are provided for nine individuals in both classes. Class 1: 87, 78, 87, 85, 93, 98, 83, 82, and 73 Class 2: 87, 86, 92, 90, 90, 91, 89, 78, and 76 According to conventions for Cohen's d, the effect size for this study is:
small
The t distributions have more _____ than the standard normal distribution.
spread