BESC 3110 (STATS)
Which of the following is an impossible value for R^2 ?
-0.1
In most distributions, nearly all (more than 99%) of the sample scores will be within what range of z-scores?
-3 to +3
One assumption of the two-sample t-test is that...
B) the two samples are independent of one another. A) the two samples are as similar as possible. ...can be helpful but not required B) the two samples are independent of one another. C) a two-tailed test will be used. ...you can use a one-tailed test D) the data have a uniform distribution ...we prefer to have normal distributions
Which of the following is a defining characteristic of experiments?
Manipulations
The sample mean is ________ and a confidence interval for the mean is _______.
a descriptive statistic; an inferential statistic
A Type I error is also called...
a false positive
If you want to use an ANOVA, your outcome variable should be...
a quantitative variable.
This predictor variable in this chart...
age
Which of the following distributions is leptokurtic?
b
Imagine a sample with n = 64 and a mean of 121 that comes from a population with a standard deviation of 16. Based on these data, what would be the 80% confidence interval for the population mean? (Use z-scores of ±1.28 for the 80% confidence level.)
(118.44, 123.56)
Imagine a sample with n = 49 and a mean of 183 that comes from a population with a standard deviation of 21. Based on these data, what would be the 99.9% confidence interval for the population mean? (Use z-scores of ±3.29 for the 99.9% confidence level.)
(173.13, 192.87)
Imagine a sample with n = 25 and a mean of 55 that comes from a population with a standard deviation of 10. Based on these data, what would be the 95% confidence interval for the population mean? (Use z-scores of ±1.96 for the 95% confidence level.)
(51.08, 58.92)
Imagine a sample with n = 49 and a mean of 60 that comes from a population with a standard deviation of 7. Based on these data, what would be the 99.9% confidence interval for the population mean? (Use z-score of ±3.29 for the 99.9% confidence level.)
(56.71, 63.29)
Imagine a sample with n = 400 and a mean of 68 that comes from a population with a standard deviation of 20. Based on these data, what would be the 90% confidence interval for the population mean? (Use z-scores of ±1.64 for the 90% confidence level.)
(66.36, 69.64)
A sample is a part of a larger...
population
If a positively skewed distribution with a mean of 100 and a standard deviation of 15 is standardized, then the shape of the new distribution will be...
positively skewed.
Which inferential test does NOT require a degrees of freedom calculation?
z-test
If X and Y in a regression equation are both expressed as z scores - zX and zY - and the correlation between the two variables is r = .3, then what is the predicted value of zY when zX = - 1.2?
-0.36
Which z-score is closest to the mean of its distribution?
-0.9
If a population has a mean of 60 and a standard deviation of 15, what is the z-score for a sample of 9 people with an average of 55?
-1
In a data set with a mean of 50 and a standard deviation of 10, what z-score would a raw score of 35 have?
-1.5
If a distribution has a mean of 30 and a standard deviation of 3, then what is the z-score for a sample of 4 scores with a mean of 27?
-2 SE = SD/sqrt(n) =3/sqrt(4) = 1.5 z= (Ms-Mp)/SE z= (27-30)/1.5 = -2
What is the predicted value of Y when X = 20 using this regression equation? Y = 12 - 0.8*X
-4
Which level of alpha for a hypothesis test has the lowest risk of a Type I error?
.01
When choosing a level of alpha for a hypothesis test, unless you have a compelling reason to do otherwise, you should use...
.05 this is the false positive (type I error rate). You use this unless you have a strong reason to do something else
Which of the following numbers is a possible value for eta-squared?
.16 eta-squared can only be positive between 0.0-1.0
If a distribution of 144 scores with a mean of 52 and a standard deviation of 12 is standardized, then the new distribution's mean will be _____.
0
In a bimodal distribution with a mean of 80 and standard deviation of 20, what would the z-score be for a raw score of 80?
0
No matter what the shape of a distribution, if it is converted to z-scores, then its mean will be...
0
What is the z-score for a sample with n = 100 and M = 103 if the population parameters are μ=100 and σ=10?
0.0
If you conduct an inferential test and retain the null hypothesis, then what is the chance of a Type I error?
0.00
If a research conducts an inferential test (such as a t-test) and rejects the null hypothesis, then what is the probability of a Type II error?
0.00 A type II error is a false negative, which is assuming that nothing is happening when something actually is. You can only get a type II error if you get a negative conclusion.
If a research conducts an inferential test (such as a t-test) and retains (i.e., fails to reject) the null hypothesis, then what is the probability of a Type I error?
0.00 The reason for this is because a type I error is a false positive. That can only happen if you have a positive that can be false. It means that you have a positive result that you have rejected the hypothesis.
If X and Y in a regression equation are both expressed as z scores - zx and zy - and the correlation between the two variables is r = -.2, then what is the predicted value of zy when zx = - 0.5?
0.1
What is the population variance for the following data? 4, 5, 5, 6
0.5
What is the interquartile range (IQR) for the these data: 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 4+
1
What is the sample standard deviation for the following data? 2, 2, 3, 4, 4
1
If a distribution has a mean of 100 and a standard deviation of 15, then what is the standard error for a sample of 225 scores?
1 This is a trick question because you don't need the mean! SE = SD/square root of (n) ..=15/15
Which of the following is an impossible value for R2?
1.10 reason is because the absolute value of R has to be less than or equal to 1 and more than 0.00
If the mean of a sample is 5 and the standard deviation is 2, then what is the z-score for a raw score of 8?
1.5
If the population mean for a distribution is 150 and the standard deviation is 20, then what is the z-score for a sample of 100 people with an average score of 153?
1.5
What is the sample standard deviation for this data set? 3, 4, 2, 4, 7
1.87
Which z-score is furthest from the mean of its distribution?
1.9
If an ANOVA is conducted and eta-squared is .10, then...
10% of the variance in the DV can be predicted by the IV(s).
What is the point estimate for the population mean if the population standard deviation is 24, the sample size is 36, and the sample mean is 110?
110
What is the predicted value of Y when X = 10 using this regression equation? Y = 30 - 1.2*X
18
What is the mode for the following data set? 1 2 2 2 2 2 3 3 3 3 4 4 4 5 5 5 5 6 6 7 7+
2
What is the median for these data? 3, 1, 2, 5+, 2, 4
2.5
What is the standard error for a distribution with σ= 40 when n = 4?
20
What is the predicted value of Y when X = 120 using this regression equation? Y = -350 + 5*X
250
If a person has a z-score of +2, what would their raw score be in a distribution with a mean of 20 and a standard deviation of 3?
26
If a population has a mean of 40 and a standard deviation of 8, what would the z-score be for a sample of 16 people with a mean of 46?
3
What is the frequency of 4 in the following data set? 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 5
3
hat is the frequency of 4 in the following data set? 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 5
3
If a test has a population mean of 70 and standard deviation of 6, then what is the z-score for a sample of n = 9 scores with a mean of 76?
3 SE=SD/squareroot of (n) z=(Ms-Mp)/SE
If a distribution has a mean of 50 and a standard deviation of 5, then a raw score of 68 would have a z-score of...
3.6
What percent of the normal distribution is between z = -1 and z = 0?
34%
What is the frequency of 2 in the following data set: 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 5
4
What is the median for the following data set? 1 2 2 2 2 2 3 3 3 3 4 4 4 5 5 5 5 6 6 7 7+
4
What is the standard error of a distribution if σ= 20 and n = 25?
4
What is the population variance for this data set? 4, 1, 6, 1
4.5
0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 5
5
What is the range for this data set? 5, 1, 2, 6, 5
5
What percent of the normal distribution is within one standard deviation of the mean (i.e., |z| < 1)?
68%
For a distribution with M = 80 and SD = 6, what is the X score for a person who has a z-score of -1.5?
71
If the mean of X is 42, the mean of Y = 72, and rxy= 0, then what is the predicted value of Y when X = 30?
72 the mean of Y. The walk through is in notes
What is the point estimate for the population mean if the population standard deviation is 10, the sample size is 100, and the sample mean is 80?
80 Trick question because the sample mean is the point estimate for the population mean. None of the rest of the info matters μ = X¯
What percent of a normal distribution is below a z-score of +1?
84%
In a normal distribution, what percent of the distribution is within between z = -3 and z = +3?
99.7%
Which is generally more accurate (in the statistical sense): a point estimate or a confidence interval?
A confidence interval
Which is generally more precise (in the statistical sense): a point estimate or a confidence interval?
A point estimate
Which is more precise (in the statistical sense): a point estimate or a confidence interval?
A point estimate
When we talk about "estimation" in statistics, what is it that is being estimated?
A population parameter
In a normal distribution, which measure of central tendency has the highest value?
All are the same
What is the null hypothesis for ANOVA?
All group means are equal
Which of the following null hypothesis statistical tests require calculating degrees of freedom?
All of them Two-sample t-test All of these tests One-sample t-test Chi-squared
For which measures is it possible to compute a confidence interval?
Any population parameter
For which levels of measurement can you calculate the mode?
Both ordinal and interval
If the dots on a scatterplot are spread out randomly, the researcher would report the correlation as:
Close to zero
Which of the following is true about regression towards the mean?
D) All of the answers are correct (look in notes) A) Predicted Y values will not always be perfect unless r = ± 1 B) Predicted Y values tend to be closer to the mean of Y than the observed values of X are to the mean of X C) Predicted Y values will have less variation than actual observed values of Y D) All of the answers are correct
What is the null hypothesis for the chi-squared test for independence?
Each group on the predictor variable (or IV) will have identical proportions in each category of the outcome variable (or DV)
What is the symbol for the test statistic in ANOVA?
F
When calculating probability values for ANOVA, the correct distribution is the...
F distribution.
If a sample's mean really is different from the comparison population's mean, then what is the easiest way to make sure that the null hypothesis would be rejected?
Getting as large a sample as possible
Which measure of variation is LEAST sensitive to outliers? Which measure of variation is LEAST sensitive to outliers?
IQR 2.5
If a researcher believes that the null hypothesis is false and wants to have the greatest chance of rejecting it with their study, then which of the following would make it more likely that the null hypothesis would be rejected?
Increasing n
What is the minimum level of measurement to calculate Pearson's r correlation coefficient?
Interval
How is a confidence interval affected when the sample size increases?
It becomes narrower
How is a confidence interval affected when the sample standard deviation decreases?
It becomes narrower
How is the point estimate affected when the sample standard deviation increases?
It does not change
If a researcher wants to compare the effects of an antidepressant to the effects of a placebo on levels of anxiety, then what is the dependent variable (that is, the DV)?
Levels of anxiety (depends on independent variable. This is the outcome variable, or the effect of the medications)
If r = .65, then the members in a sample who have _____ values on the independent variable have _____ values on the dependent variable.
Lower, lower High goes with high, and low goes with low.
When a distribution of raw scores is converted to z-scores, the mean and standard deviation of the distribution will be...
M = 0, SD = 1.
If a researcher wants to compare the effects of an antidepressant to the effects of a placebo on levels of anxiety, then what is the independent variable (that is, the IV)?
Medication: antidepressant vs. placebo A) Levels of anxiety ...dependent variable B) Antidepressant medication ...one level within the independent variable, so therefore a constant C) Two-sample t-test ...just the test you would use to get the scores D) Medication: antidepressant vs. placebo ...the manipulated variable or the cause of the effect
If a researcher wants to compare the effects of an antidepressant to the effects of a placebo on levels of anxiety, then what is the grouping variable?
Medication: antidepressant vs. placebo It is what defines the two groups that we get the means on. It is the grouping variable and the independent variable. It separates the groups and is what we are looking at to get the effects of...
Why is it better to use a one-way ANOVA than multiple t-tests to compare the means of several groups?
Multiple t-tests inflate the Type I error rate Inflate the amount of false positive rates
Which of these measures of central tendency works for nominal variables?
Neither the mean nor the median works for nominal variables.
What is the minimum level of measurement required for either of the chi-squared tests?
Nominal
If a research conducts a z-test and does not reject the null hypothesis, then...
None of the other choices is correct. A) the researcher must gather new data. B) None of the other choices is correct. C) the researcher has proven that the null hypothesis is true. D) it is not appropriate to calculate an effect size.
When open-ended scores are present in the data, which measure of variability is most appropriate? When data are negatively skewed, which measure of variability is most appropriate?
Quartiles (such as the interquartile range)
Which statistic is defined as the proportion of variance accounted in the dependent variable by the independent variable?
R-squared
Imagine that a researcher conducts a repeated measures t-test with critical values of ±2.78 and gets an observed value (or test value) of t = -3.30. What is the proper conclusion in this case?
Reject the null hypothesis t=-3.30 so it is past the range of +/-2.78 so while it is possible to occur, it is so unlikely that we should reject the null hypothesis
If you conduct a one-tailed (i.e., directional) two-sample t-test with a critical value of +2.20 and gets an observed value of t = -3.53, then what should you do?
Retain the null hypothesis
Imagine that you conduct a two-sample t-test with critical values of ±2.30 and gets an observed value (or test value) of t = -2.09. What should you do?
Retain the null hypothesis
Imagine that a researcher conducts a one-tailed (i.e., directional) two-sample t-test with a critical value of -1.83 and gets an observed value (or test value) of t = +1.98. What is the proper conclusion in this case?
Retain the null hypothesis The researcher specifically said that they wanted a one-tailed hypothesis test and that the critical value is on the negative side which means they are looking to see if the sample value is below that. The cut off value is -1.83, but we got +1.98.
Imagine that a researcher conducts a two-sample t-test with critical values of ±2.10 and gets an observed value (or test value) of t = 1.98. What is the proper conclusion in this case?
Retain the null hypothesis You only reject if the observed value is more extreme than the critical test
Imagine two studies that are identical in every respect except the size of their samples. Sample A has an effect size of d = .40 and p-value of .001. Sample B also has an effect size of d = .40 but a p-value of .10. Which sample likely had the larger sample size?
Sample A
Imagine two studies that are identical in every respect except the size of their samples. Sample A has an effect size of d = .20 and a p-value of .03. Sample B has an effect size of d = .20 and a p-value of .005. Which sample likely had the smaller sample size?
Sample A Because A and B have the same effect size. P Value has a lot to do with overlap. B has a p value of .005, so even though the value is much smaller, it's overlap is much smaller. B must have a larger sample.
Imagine two studies that are identical in every respect except their effect sizes. Sample A has a sample size of n = 80 and a p-value of .01. Sample B has a sample size of n = 80 and a p-value of .10. Which sample likely had the larger effect size?
Sample A The effect size has a lot to do with the difference between the means. Look at the z score formula. The bigger the difference between the means the larger the z score is and the smaller the p value is. Bigger sample size, smaller p value
Imagine that samples - Sample A with n = 20 and Sample B with n = 200 - are drawn from the same population and confidence intervals are computed for the same variables, which sample will likely have the more precise confidence interval?
Sample B
Imagine two samples that are drawn from the same population and measure the same variables in the same way. Sample A has a larger confidence interval than Sample B does. Which sample likely has the larger n?
Sample B Larger sample size means smaller confidence interval
Imagine that two samples - Sample A with n = 20 and Sample B with n = 200 - are drawn from the same population and confidence intervals are computed for the same variables, which sample will have the narrower confidence interval?
Sample B because it has a larger sample
Which measure requires a degrees of freedom calculation?
Sample variance
For a normal distribution, which measure of variability is most efficient (in the statistical sense)?
Standard deviation
Why is it better to use a one-way ANOVA than multiple t-tests to compare the means of several groups?
The Type I error rate gets too big with multiple t-tests
What does it mean when the result of a z-test is called "statistically significant"?
The alpha value was greater than the p-value
If you want to see whether the distribution of declared majors for incoming freshman matches a school's historic distribution of majors, then which version of the chi-squared test should you use?
The chi-squared goodness of fit test
Which version of the chi-squared test is good for examining the relationship between two variables?
The chi-squared test for independence
What is one important difference between a point estimate and a confidence interval?
The confidence interval gives two numbers instead of one
What is the null hypothesis for the chi-squared goodness of fit test?
The distribution of frequencies will match a hypothesized pattern of expected scores or frequencies
What does the symbol μX¯ refer to?
The mean of the sampling distribution of means
What does the label "Q2" refer to?
The median score or the 50th percentile
Which of the following illustrates a negative correlation?
The more often a person visits the dentist, the fewer cavities they have. As the first goes up the second goes down
If a regression equation is calculated for a sample of data and then a person who is an outlier on both X and Y is added, what would likely happen to the regression equation?
The new score would likely change both the intercept and the slope
If you conducted an experiment to compare the effects of two different online ad campaigns on the number of clickthroughs (i.e., how often people clicked on each ad), then what is the dependent variable (DV)?
The number of clickthroughs
The standard error of a sampling distribution is a function of two things:
The population standard deviation and the sample size
What does the symbol σ2 stand for?
The population variance
What is the relationship between the standard deviation and the variance?
The standard deviation is the square root of the variance
Which inferential test should be used to compare two sample means to each other?
The two-sample t-test
If you use an ANOVA to compare the means of four groups and you get a statistically significant result, what does that mean?
The variance of the group means is greater than 0.
If an ANOVA is statistically significant, what does that mean?
The variance of the group means is greater than 0. It isn't possible for variance to be negative. If it was equal to 0 that wouldn't be statistically significant
If a person has a middling score on X but a very high score on Y, what would their effect on the regression equation be?
They would raise the intercept but not change the slope
Which of the following situations is appropriate for using a chi-squared test?
To examine the relationship between major and graduation status at a university because those are two categorical variables
What is the purpose of a post-hoc test?
To find out which groups (or combinations of groups) are different from each other Post-hoc tests are inferential tests
If the dots on a scatterplot generally extend from the bottom left to the upper right of the diagram but are very widely spread out, the researcher would report the correlation as:
Weak and positive
When it is appropriate to conduct post-hoc tests?
Whenever an ANOVA is statistically significant Post-hoc test is designed to find where the significant differences are between the group means.
Which of the following distributions is mesokurtic?
a
If a person's blood sample tests positive for a disease when, in fact, the person does not have the disease, then...
a Type I error has occurred.
When the mean of the population that a sample comes from does not differ from the general population but the sample mean is nonetheless significantly different from the general population, then...
a Type I error has occurred.
In order to understand exactly how strong the relationship is between two categorical variables in a chi-squared test for independence, a research should use...
a measure of effect size like the phi coefficient. p-value is used for the inferential part, not to measure the size
If a researcher gathers data from participants before and after they participate in an exercise training program and wants to know whether their performance scores improved, then he should use...
a one-tailed, repeated measures t-test. one-tailed tells us if they improved, while a two-tailed would tell us if they were different.
Imagine a study that compared men and women (the gender factor) and who were right handed or left handed (the handedness factor) on brain function. If the the difference between right-handed and left-handed people was different for men and women, then this result would be called...
a significant interaction effect.
Imagine a study that compared men and women (the gender factor) and who were social liberal or conservative (the social attitudes factor) on levels of empathy. If the the difference between men and women was different for people who were social liberal or conservative, then this result would be called...
a significant interaction effect.
Imagine a study that compared men and women (the gender factor) and who were social liberal or conservative (the social attitudes factor) on levels of empathy. If there were significant differences between men and women, regardless of social attitudes, then the gender factor would be called...
a significant main effect A) a significant main effect. -when a factor cause is associated with a differences in means averages across all the other factors B) a significant interaction effect. -if the effect of gender was dependent on levels of social attitudes C) a spurious effect. -accident, like a type I error. There is no way of knowing this. D)a significant manipulation effect. -not a thing
Imagine a study that compared athletes and nonathletes who went to schools with or without football teams on donation levels after graduation. If there were significant differences between athletes and nonathletes, regardless of whether their school had a football team, then result for the athlete factor would be called...
a significant main effect.
Imagine a study that compared men and women (the gender factor) and who were social liberal or conservative (the social attitudes factor) on levels of empathy. If there were significant differences between people with liberal and conservative social attitudes, regardless of gender, then the attitude factor would be called...
a significant main effect.
If you want to compare the means of two different groups to each other then you should use...
a two-sample t-test.
If a web marketer compares the effectiveness of two online ads in getting clicks by gathering data from 3 million Internet shoppers, the population of interest is...
all internet shoppers
In order to conduct an ANOVA, the dependent variable (DV) must be...
an interval or ratio level variable.
A sampling distribution can be calculated for...
any sample statistic.
As the means of two groups become more similar, Cohen's d will...
approach 0.
Compared to a mesokurtic distribution, the tails of a leptokurtic distribution...
are longer
When people who score low on one variable tend to score low on another variable, then those two variables...
are positively correlated. Negatively correlated would mean that one is higher and the other is lower
A histogram is not appropriate when the data are...
at the nominal or ordinal level of measurement.
Which type of chart would be most appropriate for a nominal variable?
bar graph
If a distribution of raw scores has a strong negative skew, then, given a sufficiently large n, the sampling distribution of means for that distribution will...
be normal.
When the range of confidence for a confidence interval becomes lower - from 90% to 80%, for example - then the confidence interval will...
become narrower.
When the range of confidence for a confidence interval becomes higher - from 80% to 99%, for example - then the confidence interval will...
become wider when you increase the level of confidence it becomes wider because you have to use a different z score.
As the standard deviation for a distribution increases, then the corresponding confidence interval will...
become wider.
A distribution that has two distinct peaks is referred to as...
bimodal
A distribution with two distinct peaks can be described as...
bimodal
When a histogram or polygon chart for a quantitative variable has two distinct peaks, then the distribution is referred to as _____.
bimodal
A chi-squared test is conducted when...
both of the variables are nominal/ordinal data.
A chart of this type is called a...
box plot
A major advantage of the chi-squared tests is that they...
can be used with any level of measurement.
One of the major advantages of the chi-squared tests is that they...
can be used with nominal, ordinal, interval, or ratio data.
What is the mean for these data? 3, 1, 2, 5+, 2, 4
cannot be calculated
What is the range for this data set? 5, 3, 7+, 1, 4
cannot be calculated
One good use of the range is to...
check for outliers
The probability distribution that is used in the chi-squared test is the...
chi-squared distribution.
The analysis of variance is useful if you want to...
compare the mean incomes of people in several different jobs.
The analysis of variance (or ANOVA) is the preferred inferential test when you need to...
compare the means of three or more groups.
The analysis of variance would be appropriate if you wanted to...
compare time to graduation for people at different universities.
The variable that is measured as the outcome in an experiment is called the _____ variable.
dependent
Inferential statistics are typically contrasted with _____ statistics.
descriptive
The comparison group in a repeated-measures t-test is...
each person's own score at time 1.
The comparison group in a repeated measures t-test is...
each person's own score at time 1. We are analyzing the difference between each person's time 1 and time 2 scores, but that isn't the COMPARISON GROUP. Each person is serving as their own control.
A question that asks a person how strong their motivations for religious participation are using a 1-7 rating scale is at _____ level of measurement.
either ordinal or interval
If you need to calculate an effect size for ANOVA, what would the best choice be?
eta-squared
What is the most common measure of effect size for ANOVA?
eta-squared
In calculating a chi-squared tests, the observed frequencies in each category are compared to...
expected frequencies.
Correlations (using the Pearson product moment correlation coefficient) may be uninterpretable and inappropriate if the data...
have a nonlinear relationship.
The distribution is...
him. It is positively skewed
A chart of this type is called a...
histogram. It is positively skewed
A score's frequency is determined by...
how often it occurs in the data set.
In an experiment, the variable that the researcher manipulates is called the _____ variable.
independent
"Estimation" refers to a class of...
inferential statistics.
The chi-squared tests are examples of...
inferential statistics.
The chi-squared tests are...
inferential statistics/procedures.
If the number of games a team has lost in a season is subtracted from the number of games that they won in that season, the resulting variable would be at the _____ level of measurement.
interval
Temperature in celsius or Fahrenheit (but not Kelvin) is measured at which level of measurement?
interval
What is the minimum level of measurement needed to calculate the mean?
interval
What is the minimum level of measurement to calculate a Pearson's r correlation coefficient?
interval this is because you need to be able to calculate means
The standard normal distribution...
is a bell curve with M = 0 and SD = 1.
The most important difference between Cohen's d and the t-test is that Cohen's d...
is not affected by sample size.
In a two-tailed or non-directional test, if the critical value has a greater absolute value than the observed (or test) value does, the the null hypothesis...
is not rejected (i.e., retained). If a critical value has a greater value than the observed test value then the null hypothesis is not rejected
A uniform distribution...
is platykurtic.
One reason that researchers nearly always gather data from samples of participants instead of entire populations is because..
it can be impractical or even impossible to study populations.
How is a point estimate affected when the sample size increases?
it does not change
One reason that researchers nearly always gather data from samples of participants instead of populations is because..
it is easier to gather data from samples than populations.
When calculating an effect size for the z-test...
it is most common to use Cohen's d.
A researcher who wants to use a z-test to compare a sample mean to a population mean must first...
know the population standard deviation.
In order to compute a one-sample z-test you must...
know the population standard deviation.
A narrow distribution that is sharply pointed in the middle and that has many outliers is called...
leptokurtic.
Imagine that a researcher is interested in whether residents in his local area have higher levels of well-being than the national average. What would be an appropriate alternate hypothesis for a one-tailed or directional z-test for this test?
local residents average > national average
If r = -.4, then the people who have _____ values on the predictor variable generally have _____ values on the outcome variable.
lower, higher
For a study to be considered an experiment, it must have...
manipulation
If a distribution of raw scores has a strong positive skew, then, given a sufficiently large n, the mean of the sampling distribution will be equal to the _____ of the raw score distribution.
mean
In a positively skewed distribution, which measure will generally have the highest value?
mean
Which measure of central tendency is MOST influenced by outliers?
mean
The three most common measures of central tendency are:
mean, median, mode
Which measure of central tendency is most appropriate for skewed distributions?
median
Which of these measures is LEAST affected by outliers?
median
The distribution of all possible sample variances - if n is sufficiently large (e.g., n > 30) - will be...
mesokurtic
In a negatively skewed distribution, which measure will generally have the highest value?
mode
Which measure of central tendency is LEAST efficient?
mode
Which measure of central tendency works for nominal variables?
mode
What is the degrees of freedom for the sample variance?
n-1
What is the formula for the degrees of freedom (df) for a two-sample t-test?
n-2
As the size of samples in a sampling distribution increases (i.e., as n get bigger), then that distribution becomes...
narrower
Compared to a mesokurtic distribution, the peak of a leptokurtic distribution is...
narrower and higher.
A normal distribution has a value of skewness that is _____.
near zero
If the dots on a scatterplot generally extend from the top left to the bottom right of the diagram but are very widely spread out, the researcher would report the correlation as...
negative but weak.
A normal distribution generally has _____ skew.
no
A question that asks a person which religion (if any) they identify with is at the _____ level of measurement.
nominal
A variable that classifies people into racial or ethnic groups is what level of measurement?
nominal
If a person's sex is coded as Male = 0 or Female = 1, then that variable is at the _____ level of measurement.
nominal
The only level of measurement that does not place scores or categories into order (and is therefore the lowest level of measurement) is the _____ level of measurement.
nominal
The respondent's gender is typically recorded as a(n) _____ variable.
nominal
What is the minimum level of measurement needed to calculate the mode?
nominal
A frequency bar graph would be most appropriate for which measurement scales?
nominal or ordinal
As the size of samples (n) in a sampling distribution increases, the shape of that distribution becomes more...
normal
The Central Limit Theorem states that the shape of a sampling distribution becomes closer to what shape as the number of sample means in the distribution increases?
normal
The central limit theorem says that when all possible samples of a sufficient size are taken from a population and their means are charted, that distribution of means will be...
normally distributed.
Compared to a mesokurtic distribution, the peak of platykurtic distribution is...
not as high
If a person has a z-score of 1 on a test, then their score is...
one standard deviation above the mean.
A univariate analysis typically focuses on...
one variable at a time.
The version of ANOVA that is used to compare, for example, the well-being of people from the three largest countries in North America is called the...
one-way ANOVA the one category is North America
A question that asks whether a person believes they are more creative, less creative, or just as creative as other people is at the _____ level of measurement.
ordinal
What is the minimum level of measurement needed to calculate the median?
ordinal
In this boxplot, the circles on the right side of the box indicate...
outliers
A confidence interval specifies a range of values for a parameter estimate, whereas a(n) _____ specifies just a single value for that parameter.
point estimate
If you can use only one number to estimate a population parameter, then the best value is a...
point estimate.
Which is bigger: a sample or a population?
population
A distribution such as income that has most of the people at the bottom or middle but a few people with extremely high scores, is referred to as...
positively skewed
A histogram is appropriate when the data are...
quantitative
What is the non-directional null hypothesis for correlation?
r = 0 (or rho = 0)
Which measure of variation is most influenced by outliers?
range
A question that asks how many times a person attends religious services each year is at the _____ level of measurement.
ratio
A variable that records how many seconds it take for a person to spell a word backwards is at the _____ level of measurement.
ratio
The amount of time that a person spends on social media each week in minutes is a(n) _____ variable.
ratio
The highest level of measurement (i.e., the one that contains the most information) is the _____ level of measurement.
ratio
The number of students enrolled in a school each year is an example of which level of measurement?
ratio
What is the highest level of measurement?
ratio
Which level of measurement has a true zero point?
ratio
When a distribution of raw scores is converted to z-scores, the shape of the distributions...
remains the same.
When a regression equation doesn't predict a person's score perfectly, then the difference between their predicted score and their actual score is the...
residual
The difference between a predicted Y score and an actual observed Y score is known as the...
residual.
If a researcher conducts a t-test with an alpha of .01 and gets a p-value of .25, then the researcher should...
retain (i.e, fail to reject) the null hypothesis.
1.96 for a z-test and gets an observed z (i.e., test value) of +0.55 for a sample of n = 40, then the researcher should...
retain (i.e., fail to reject) the null hypothesis.
If a researcher is using an critical value of ±1.96 for a z-test and gets an observed (or test) z of -1.73, then the researcher should...
retain (i.e., fail to reject) the null hypothesis.
If a researcher is using an alpha of .05 for a z-test and gets an observed (or test) p-value of .23, then the researcher should...
retain (i.e., fail to reject) the null hypothesis. We have a 23% chance of getting a sample effect this big through random error then that is too big. It needs to be less than 5% before we suspect something big is going on.
If a researcher is able to survey 99% of all students enrolled in statistics classes at a college, then that researcher has gathered data from a(n)...
sample
If a researcher conducts a chi-squared test for independence using an alpha of .05 and gets an observed p-value of .04, then she...
should reject the null hypothesis. you want the observed p-value to be bigger than the alpha, so this doesn't qualify
If a researcher conducts a chi-squared goodness-of-fit test using an alpha of .05 and gets an observed p-value of .10, then she..
should retain (i.e., fail to reject) the null hypothesis because the observed value of p is greater than the critical value of p
If a researcher conducts a chi-squared test for independence using an alpha of .01 and gets an observed p-value of .04, then he...
should retain (i.e., fail to reject) the null hypothesis. you want the observed p-value to be bigger than the alpha
If you were to conduct a chi-squared test for independence using an alpha of .01 and you got an observed p-value of .02, then you...
should retain the null hypothesis.
What are the values of skewness and kurtosis for a normal distribution?
skewness = 0 and kurtosis = 0
A population can never be...
smaller than one of its samples.
Which of the following is NOT a measure of central tendency?
standard deviation
Cohen's d indicates the number of...
standard deviations between two means.
As the mean for a sample becomes greater, the width of the corresponding confidence interval will...
stay the same because the mean doesn't affect the width of the confidence interval
As the mean for a distribution increases, then the width of the corresponding confidence interval will...
stay the same.
In an experiment that looks at the effect of different teaching methods on student learning, the independent variable is...
teaching method
In a study that looks at the relationship between gender and college major, a statistically significant chi-squared test for independence would mean...
that the distribution of college major varied by gender and the distribution of genders varied by college major.
In a study that looks at the relationship between handedness and intellectual giftedness (which, by the way, are related), a statistically significant chi-squared test for Independence would mean...
that the distribution of giftedness varied by handedness and the distribution of handedness varied by giftedness.
One visual difference between a bar chart and a histogram is that in a histogram...
the adjacent bars touch but in a bar chart they are separate.
A bivariate analysis typically focuses on...
the association of two variables.
The word "independence" in the chi-squared test for independence means...
the distribution of frequencies on the outcome/dependent variable is unrelated to the categories of the predictor/independent variable.
According to the Central Limit Theorem, the mean of the sampling distribution of means μX¯ - will equal...
the mean of the original population.
Which of the following measures of central tendency can be used with data on the ratio level of measurement?
the mean or the mode
When the means of two samples are being compared and Cohen's d = 1.10, then...
the means are 1.1 standard deviations apart.
When the means of two samples are being compared and Cohen's d = 0, then...
the means are identical.
If a researcher wants to test whether an experimental group is different from the general population, the she would test...
the null hypothesis of no difference between the group and the population. We test the null (opposite of what we want) to see if there is an exception for it. This is much easier to prove that there is an exception to things.
The degrees of freedom for chi-squared tests are based on...
the number of categories in the variable(s).
The most common measure of effect size for the chi-squared test for independence is...
the phi coefficient phi is a version of the correlation coefficient
If you draw a picture of the null distribution with the critical values and regions of rejection marked, then the alpha level is represented by...
the proportion of the distribution in the regions of rejection.
The blue box in this chart represents...
the range for the middle 50% of scores.
The z-test is appropriate when...
the researcher knows the population mean and variance/standard deviation
If a researcher is using alpha = .01 and gets a p-value for the z-test of p = .005, then...
the researcher should conclude that the results are unlikely to occur by chance if the null hypothesis is true.
The vertical distance between a person's predicted score on Y and their actual score on Y is called _____ and it signifies _____.
the residual; error in prediction
If a researcher is using alpha = .05 and gets a p-value for the z-test of p = .02, then...
the results are unlikely to occur by chance if the null hypothesis is true.
A Type I error occurs when...
the sample data lead us to reject a null hypothesis that is true. This is a false positive. Because of a sampling error (or a sample with a really high mean) this occurs
A Type II error occurs when...
the sample data lead us to retain (i.e., fail to reject) a null hypothesis that is false. False negative. This means that there really is something going on and we should have rejected it but our sample data didn't lead us to that.
If a researcher is comparing a sample mean to a population mean and gets Z score = -2.0, this means that...
the sample mean is standard errors away from the population mean
If a researcher is comparing a sample mean to a population mean and gets Cohen's d = -2.0, this means that...
the sample mean is two standard deviations below the population mean.
A point estimate for the population mean is based on...
the sample mean.
When calculating an effect size for the z-test...
the sample size is irrelevant.
The distribution of all possible sample means (of a given size) is called...
the sampling distribution of means.
The distribution of all possible samples of a given size (e.g., n = 54 or n = 117) are taken from a population and their means are charted, that distribution is known as...
the sampling distribution of means.
The distribution of all possible sample variances (of a given sample size) is called...
the sampling distribution of variances.
If a person were to create a sampling distribution for sample standard deviations, then the mean of that distribution would be equal to...
the standard deviation of the original distribution.
The standard error is...
the standard deviation of the sampling distribution.
In order to calculate eta-squared, you first need to know...
the sum of squares (SS)
The chi-squared tests are called "non-parametric" tests because...
they do not make assumptions about population parameters.
If the formula for the population standard deviation were used with sample data, then result would be...
too small
A two-sample t-test is an appropriate test when..
two samples are being compared on an interval or ratio level variable. Because we can compute the means on both of these levels.
According to the Central Limit Theorem, if a research takes sufficiently large samples (e.g., n > 30) from a bimodal distribution, then the resulting sampling distribution will be...
unimodal
When a histogram for a quantitative variable has only one distinct peak, then the distribution is referred to as...
unimodal
If a researcher used a one-sample z-test to determine whether an experimental group was different from a general population, what she would actually be testing is...
whether their means are different.
When scores in a data set are very close to one another, then the variance...
will be close to 0.
If scores in a data set are very different from each other, then the standard deviation...
will be high
When the means of two groups are the same, then Cohen's d...
will equal 0.
If X and Y in a regression equation are both expressed as z scores -zXandzY- then what can never happen?
zY > zX
If n = ∞, then what is the critical value of t for alpha = .05?
±1.96
If n = ∞, then what is the critical value of t for alpha = .05?
±1.96 t distribution is like the d. It get's squished the smaller the sample. As the sample gets larger the t matches the normal distribution
