STATs FINAL EXAM QUIZZES

A researcher measures the relationship between time spent playing video games in hours and cognitive performance. If SS(xy) = 40, SS(x) = 200 and SS(y) = 100, then what is the value of the correlation coefficient?

.28

A researcher conducts a two-independent sample t-test with a sample of 24 participants (12 per group). What are the degrees of freedom?

11

What are the degrees of freedom between persons for a study with n=12 participants observed in 4 groups?

11

A researcher records M=12 in a sample of men (n=10) and M=8 in a sample of women (n=20). What is the weighted mean for these samples?

12x10 + 6x20=280/ (20+10)= 9.33

A researcher measures the following scores: 14, 12, 12, 11, 9,9, 8 and 5. What is the range of these data?

14-5 = 9

If the coefficient of determination is 0.60 and SS(y) = 280, then what is the sum of squares regression for an analysis of regression?

168

A researcher computes a mean square residual equal to 4.29. What is the value of the standard error of the estimate?

2.07

If the smallest score in a distribution is 10 and the largest is 32, then what is the real range for these data?

23

A researcher measures the following data: 0,0,2,4,5,8,9,11, and 12. What is the value of the median quartile?

5

Following a significant one-way within subjects ANOVA, we find we need to make 3 pairwise comparisons. What is the testwise alpha level if we want to ensure that the expermentwise alpha level is .05?

A. .05 B. .02 C. .15 D. depends on the value of the mean square error

A researcher measures the following correaltion: r= +.38. What is the value of the coefficient of determination?

A. .14

Unlike t-tests, the two-way ANOVA can be used when:

A. the same participants are observed across groups B. different participants are observed across groups C. two groups are observed in the same study D. the levels of two factors are combined

A negative correlation indicates that:

As one factor increases the other factor decreases

A researcher conducts a one-independent sample t-test with a sample of 12 participants. What are the degrees of freedom for this hypothesis test?

B. 11

Which of the following is a source of variation in the one-way between-subject's ANOVA that you would like to maximize

Between groups variation

A bar chart is similar to a histogram, except in a bar chart, each rectangle __________ the adjacent rectangles at the boundaries of each interval.

Does not touch

It is necessary to create intervals for a simple frequency distribution with what type of data?

Grouped data

The mean is used to describe:

Interval scale data

The mean for a distribution of scores is M = 6. If we measure a new score equal to 10, what will happen to the mean? It will ____________.

It will increase

A Cohen's d of .55 would be considered a ___________ effect size.

Medium to large effect

A researcher records the following time in seconds that children with a toy: 12, 14, 10, 6, 8, 10, 13, 12, 4, 12, and 6. Which measure of central tendency is largest?

Mode

The ______________ is the value in a data set that occurs most often.

Mode

The ________is the value in the data set that occurs most frequently.

Mode

The _____________is the square root of the _______________.

Standard deviation; variance

Homogeneity of variance refers to the assumption that:

The variance of scores in each population is approximately equal

Which of the following is NOT an assumption of the two-way between-subjects ANOVA?

a. normality b. random sampling c. homogeneity of variance d. homogeneity of covariance

In the case of tied ranks when calculating the Spearman's correlation, the researcher will need to:

add the ordered tied ranks and divide by the number of tied ranks added.

A measure of the proportion of variance in one factor (Y) that can be explained by known values of a second factor (X) is called:

coefficient of determination

A statistical procedure used to describe the strength and the direction of the linear relationship between two factors is called a:

correlation

When pairs of scores for two factors change in the opposite directions, the slope of the regression is _____________.

negative

A characteristic in a population is called a ____________, whereas a characteristic in a sample is called a _____________.

parameter....statistic

Scatter grams can be used to illustrate the relationship between ______________.

Two variables, data points, bivariate plots

The weighted mean is used to compute the mean for sample with _______________sizes.

Unequal

The assumption that there is an equal variance of data points dispersed along the regression line is called:

homoscedasticity

Qualitative variables tend to be on which scale of measurement?

Nominal and ordinal scales

The standard deviation is most informative for describing what type of distribution?

Normal distribution

The mean is the balance point of the distribution, which means that it is:

Not always Located in the center of the normal distribution

An analysis of regression for one predictor variable is computed using a sample of 28 participants. What are the degrees of freedom associated with regression variation?

1

A researcher computes the following test statistic for a two-independent sample t-test: t(22) = 3.14, p<.05. What is the proportion of variance for this test using omega-squared?

A. .28 B. .31 C. .34 D. not enough information

How many interactions are possible in the two-way between-subjects ANOVA?

A. 0 B. 1 C. 2 D. 3

A researcher reports that emotional responses varied by the type of stressor in a controlled environment, F(4,55) = 6.01, p<.05. How many participants were observed in this study?

A. 12 B. 55 C. 59 D. 60

If a study is conducted and the researcher has found that after calculating a one-way between subjects ANOVA that the SS total =175 and the SSwithin or SSe = 150. What is the variation BETWEEN groups?

A. 150 B. 25 C. 175 D. Not enough information

What are the degrees of freedom in the denominator for a study with n=10 in each of three groups?

A. 2 B. 3 C. 27 D. 30

What are the degrees of freedom numerator for a study with n=12 in each of four groups?

A. 3 B. 4 C. 32 D. 36

What is the critical value for a study with 2 (between groups) and 27 (error) degrees of freedom at a .05 level of significance?

A. 3.32 B. 3.35 C. 5.49 D. the critical value is not listed

A researcher conducts a study in which 12 different participants are observed at each combination of two factors, where factor A has 3 levels and Factor B has 2 levels. What are the degrees of freedom for error? **remember the formula is: pq(n-1)

A. 6 B. 66 C. 71 D. 72

Which post hoc test is associated with the greatest power to detect an effect?

A. Fisher's LSD B. Tukey HSD C. One-way between subjects test D. comparisons with a Bonferroni adjustment

Which of the following is an assumption of the one-way within subjects ANOVA but not the one way between subjects ANOVA?

A. Normality B. random sampling C. homogeneity of variance D. homogeneity of covariance

A researcher conducts two studies on social influence. In Study 1, 24 participants are randomly assigned to one of three situations. An equal number of participants are assigned to each situation. Study 2 is similar except that k=3 and n=8. If SSbet = 28 and SSWithin (SSe) = 42 in both studies, then in which study will the decision be to reject the null at the .05 level of significance?

A. Study 1 B. Study 2 C. Both D. Neither

Which of the following is a common reason to include a second factor in a research design?

A. a hypothesis may require that we observe two factors. B. to ensure that enough participants are included in a study C. to control for threats to validity D. both a and c

A researcher conducts a study in which the same group of participants are observed at each combination of levels for two-factors. Which type of design is described for this ANOVA?

A. between-subjects design B. within-subjects design C. mixed design D. a one-way mixed design

When we arrange the raw data in an ANOVA test in a table, the combination of one level from each factor is called a:

A. cell

Which of the following is a limitation for interpreting a significant correlation coefficient?

A. correlations do not show cause B. outliers can change the value of a sign of a correlation C. data should not be interpreted beyond the range of the data measured = all of the above

Homogeneity of variance refers to the assumption that:

A. data in the population or populations being sampled are normally distriibuted B. the variance of scores in each population is approximately equal= correct C. the probablities of each measured outcome in a study are independent D. the data were selected using a random sampling procedure

What value is placed in the denominator of the formula for the estimated Cohen's d for a two-independent sample t-test?

A. estimated standard error B. population standard deviation C. pooled sample standard deviation D. estimated standard error for the difference

To compute the Bonferroni procedure, we divide ____________ by the total number of pairwise comparisons.

A. experimentwise alpha B. the p value for each test C. testwise alpha D. the mean square error

A main effect is a source of variation associated with MEAN differences:

A. in the cell means in a table summary B. across the combination of levels of two factors C. across the levels of a single factor D. across the combination of levels of two or more factors

How does selecting related samples minimize the estimate for standard error?

A. it allows us to compute difference scores prior to computing the test statistic B. it eliminates the between-persons sources of error C. it decreases the likelihood of a Type I error D. both a and b

Three advantages for selecting related samples include all of the following EXCEPT:

A. it can be more practical B. it increases power C. it increases your sample size D. it minimizes the estimate for the standard error

A researcher compares differences in personality traits among pairs of identical twins. What type of research design did the researcher use?

A. matched-pairs design B. repeated measures C. 2 sample independent t-test D. z test for 2 related groups

A researcher reports the following result for a t-test at a .05 level of significance: t(40) = 3.02, p<.05 (d =.22) Is this result significant?

A. no, the p value is less than 5% B. yes, for only a one-independent sample t-test C. yes, for a two independent sample t-test D. yes, for both a one and two-independent sample t-test

The one-way between-subjects ANOVA is used when different participants are assigned to ______group(s).

A. one B. two C. two or more D. any of the above

Which of the following is a type of repeated measures design?

A. pre-post design B. within-subjects design C. matched pairs design D. both a and b

An advantage of computing difference scores in the related samples t-test is that it:

A. reduces variability B. reduces standard error C. increases power D. all of the above

A researcher randomly assigns 33 adults to observe a short video clip of a person preparing a low or moderate or high fat meal. Participants rated how likely they would be to consume the meal. If MS bet = 20 and MS within = 3.85, than what was the decision at a .05 level of significance?

A. reject the Null B. Fail to reject/Retain the Null C. need more information D. Can't determine because you have committed a Type I error.

The related samples t-test can be computed when:

A. the same participants are observed two times or in two groups B. the sample is selected from a population with a known variance C. different participants are observed in each group D. the same participants are observed in 3 or more groups

The two-independent sample t-test can only be computed when:

A. the same participants are repeatedly observed B. the sample selected from a population from a known variance C. the sample size is larger than the population D. different participants are observed one time in each group

Which of the following is an assumption of the one-independent sample t-test?

A. the sample data are normally distributed B. participants were randomly selected C. different participants were observed in two or more groups D. all of the above

What value is placed in the denominator of the formula for estimated Cohen's d for the one-independent sample t-test?

A. the standard error B. the estimated standard error C. the population standard deviation D. the sample standard deviation

Which of the following changes will increase power?

A. the sum of squares between increases B. the sum of squares error decreases C. the mean square error decreases D. all of the above

To report the results of a one-independent sample t-test, which of the following is not reported

A. the test statistic B. the p value C. the degrees of freedom D. the critical values

To report the results of the one-way within subjects ANOVA, which of the following is NOT reported?

A. the test statistic B. the p value C. the degrees of freedom between persons D. the degrees of freedom between groups

To report the results of the two-way between subjects ANOVA and post hoc tests, which of the following is reported?

A. the test statistic for each significant main effect and interaction B. the p-value for each significant main effect and interaction C. the post hoc tests used to analyze significant main effects D. all of the above

Which of the following is a source of variation in the one-way within subjects ANOVA but NOT in the between-subjects ANOVA?

A. within-groups variation B. between persons variation C. between groups variation D. both a and b

Which of the following is a source of variation in the one-way between-subjects ANOVA that you would like to maximize?

A. within-subjects B. between-subjects variation C. between groups variation D. both b and c

researcher reports the following interaction: F(2,44) = 3.11. Is the p value less than .05 for this test?

A. yes, because the critical value is larger than 3.11 B. no, because the critical value is larger than 3.11 C. no, because the critical value is smaller than 3.11 D. not enough information

A researcher reports that cultural stereotypes varied by the type of situation a participant experienced, F(4,40) 2.89. Is the p value less than .05 for this test?

A. yes, because the critical value is smaller than 2.89 B. yes, because the critical value is larger than 2.89 C. no, because the critical value is smaller than 2.89 D. no, because the critical value is larger than 2.89

The research method used to demonstrate that one variable causes changes in a dependent variable is called the:

An experiment or correlational study

A researcher conducts a two-independent sample t-test. What are the critical values for a two tailed hypothesis test with a .05 level of significance with 14 partcipants in each group.

Answers: A. + or - 2.179 B. + or - 2.145 C. + or - 2.048 D. + or - 2.056

The __________________is a research method where two variables are measured for each participant, and the extent to which those variables are related is measured.

Correlational

When we sum the frequencies across a series of intervals, the summary is called a:

Cumulative frequency distribution

An ogive is used to summarize what type of frequency distribution?

Cumulative percent

A relative percent distribution is often used instead of a relative frequency distribution because

People think it is easier to understand percent than decimals

The correlation coefficient used to measure the direction and strength of the linear relationship of two ranked factors on an ordinal scale of measurement is called the:

Spearman correlation coefficient

The sum of the deviation of scores from their mean is 0. To avoid this result, each deviation is _________.

Squared

A frequency polygon is a dot and line graph where the dot is the ____________ of each interval and the line connects each dot.

The midpoint

A researcher summarizes a set of data by describing the score that occurred most often. What type of statistics did the researcher use to summarize these data?

The mode

The _____________is the sum of N scores divided by N, whereas the ____________ is the sum of n scores divided by n

The population mean; sample mean

An analysis of regression measures only the variance in ___________ because it is the value we want to predict.

Y

Values of the ____________ variable are known and can be used to predict values of the _______________ variable.

predictor; criterion

The more variance in Y, the criterion variable, that we attribute to changes in X, the predictor variable, the larger the:

regression variation

The ___________of the correlation coefficient indicates the direction of the correlation.

sign

A statistical procedure used to compute the slope (b) and y-intercept (a) of the best fitting straight line to a set of data points is called:

the method of least squares

An estimate of the standard deviation or distance that a set of data points falls from the regression line is called:

the standard error of the estimate

A researcher studies food intake by recording two measures: the type of food consumed (high fat, low fat) and the number of calories consumed. Which is a nominal scale measure?

the type of food consumed

A researcher tests the extent to which the timing of a stimulus presentation, X can be used to estimate the frequency of a behavioral response, Y. Which factor is the predictor variable?

timing of the stimulus presentation

A one-way within-subjects ANOVA is used when the same participants are observed in _____________group(s).

two or more