PSY Basic STATS CH. 15-17

A researcher computes a 4 ´ 6 chi-square test for independence with a sample of 120 participants, with c2 = 14.79. What is the effect size for this result?

.20

A researcher measures the relationship between two variables, X and Y. If SSXY = 340 and SSXSSY = 320,000, then what is the value of the correlation coefficient?

.60

A researcher selects a sample of 110 participants and computes the following phi correlation coefficient: rj = .31. What is the value of c2?

10.57

A researcher reports the following equation for a best-fitting straight line to a set of data points: Y^hat = -1.01X + 3.24 . Which value is the y-intercept?

3.24

A researcher computes a 2 ´ 2 chi-square test for independence. What is the critical value for this test at a .05 level of significance?

3.84

A researcher records the frequency of participants selecting one of four new slogans for an advertising campaign. If it was expected that among 200 people polled there would be no preference for any one slogan, then what was the expected frequency for each slogan.

50 people

If the coefficient of determination is .30 and the sum of squares regression for an analysis of regression is 210, then what is the value of SSY?

700

Select the description below that identifies the following correlation: r = .28, p < .01.

All of These: The correlation is positive. The correlation is statistically significant. The coefficient of determination is .08.

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

All of these: Correlations do not demonstrate cause-and-effect. Outliers can change the direction and/or strength of the correlation. Conclusions should not be drawn beyond the range of scores measured.

Which of the following is a step to evaluate the significance for the relative contribution of each factor?

All of these: find r2 for the "other" predictor variable complete the F table and make a decision identify SS accounted for by the predictor variable of interest

Which of the following is an appropriate measure of effect size for a 2 ´ 2 chi-square test for independence?

All of these: proportion of variance the phi coefficient Cramer's V

To summarize the chi-square goodness-of-fit test, which of the following is reported?

All of these: test statistic p value degrees of freedom

To summarize correlations, we report:

All of these: the strength of the correlation the direction of the correlation the p value

Which of the following measures of effect size can be reported with a 3 ´ 4 chi-square test for independence?

Cramer's V

A chi-square goodness-of-fit test leads to a decision to retain the null hypothesis. Which of the following correctly explains this decision?

Frequencies observed were statistically similar to the frequencies expected at each level of the categorical variable.

What is the problem with the following data for computing a correlation? Factor 1 3 3 3 3 3 Factor 2 3 3 3 3 3

IT IS NOT: The correlation coefficient will equal 1.0 because it violates the assumption of linearity. MAYBE: The correlation coefficient will equal 1.0 because it violates the assumption of normality

A researcher measures the correlation between the frequency of self-esteem (high, low) and health status (lean/healthy, overweight/obese). Based on the frequencies for each nominal category given below, what is the value of the phi correlation coefficient? Health Status Lean/Healthy Overweight/Obese Self-Esteem Low 18 32 High 32

IT IS NOT: .52

A researcher reports the following regression equation for two variables, X and Y: . If X = 2.30, then what is the value of y?

IT IS NOT: 10.23 MAYBE: 13.23

A researcher measures the following correlation between cost of produce and number of units sold. Which description best explains the relationship between these two factors?

Less expensive produce is associated with an increased number of units sold.

Which of the following statements is true regarding the sources of variation present in an analysis of regression?

The closer that data points fall to the regression line, the more the variance in Y will be attributed to regression variation.

A researcher measures the following correlation between cups of coffee consumed daily and daily work schedule. Which description best explains the relationship between these two factors?

The more a person works, the more coffee he or she tends to drink.

Which of the following is a key assumption for a chi-square goodness-of-fit test?

The observed frequencies are independently recorded in each cell.

A researcher computes the following analysis of regression table. Based on the data given, what is the decision for this test at a .05 level of significance? (Note: Complete the table first.) Source of Variation SS df MS F Regression 1 28 Residual Total 118 19

X significantly predicts Y.

The more that the variability in ______ is associated with regression variation, the more likely it is that X predicts Y.

Y

Which of the following equations is appropriate for a linear regression with three predictor variables?

Y= b1X1 + b2X2 + b3X3 + a

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

a correlation

The scores or data points for a regression analysis are typically reported in

a scatter plot

The correlation coefficient ranges from -1.0 to +1.0, with values closer to ±1.0 indicating ______.

a stronger relationship between two factors

Which of the following is used to determine the significance of predictions made by a best fitting linear equation?

analysis of regression

To appropriately interpret the chi-square goodness-of-fit test, it is necessary to compare differences ______ of the categorical variable.

at each level

The method of least squares is used to determine the ______ straight line to a set of data points.

best-fitting

One key advantage for including multiple predictor variables in the equation of a regression line is that it allows you to

detect the extent to which two or more predictor variables interact

Many nonparametric tests are called ______ because they make no assumptions regarding the shape of the distribution in the population.

distribution-free tests

A chi-square goodness-of-fit test shows that the frequencies observed equal those that were expected. Hence, the value of the test statistic is

equal to 0

Which of the following is recorded using a chi-square goodness-of-fit test and a chi-square test for independence?

frequency observed and frequency expected

A researcher can correct for having expected frequencies smaller than five by

increasing the number of cells and increasing the sample size

One way a researcher can correct for having expected frequencies smaller than five is to increase the sample size such that

it is five times larger than the number of cells

The degrees of freedom for a chi-square goodness-of-fit test are

k - 1

Which of the following is used to determine the linear equation that best fits a set of data points?

method of least squares

We convert r to a chi-square statistic for which of the following correlation tests?

phi

We convert r to a t statistic for which of the following correlation tests?

point-biserial

We compute the frequency expected in each category using known ______ stated in the null hypothesis.

proportions

A researcher measures the correlation between gender and student aptitude scores from 0 to 100 among 20 participants. If rpb = .49, then what is the decision for this correlation test?

reject the null hypothesis

A researcher observes a correlation of values from 2 to 10 points and draws conclusions about the full range of values in the population from 0 to 21 points. Which limitation for correctly interpreting a correlation coefficient did the researcher violate?

restriction of range

A researcher computes the following phi correlation coefficient: rj = .42. If the sample size was 20, then what is the decision for this correlation test?

retain the null hypothesis

The appropriate correlation coefficient for measuring the direction and strength of the linear relationship between one continuous and one dichotomous variable is

the point-biserial correlation coefficient

The coefficient of determination is mathematically equivalent to ______. A. the correlation coefficient

w2

A researcher computes a perfect negative correlation, in which each data point falls exactly on the regression line. In this example, the value of the standard error of estimate will be

equal to 0

If r = .65 and n = 36, then what is the value of c2?

15.21

A researcher reports the following results for a chi-square test: c2 () = 5.39, p < .05 (V = 0.22). What is the maximum number of levels that an independent variable could have had?

2

If the coefficient of determination is .25 and the sum of squares residual is 180, then what is the value of SSY?

240

A researcher computes a 2 ´ 4 chi-square test for independence. What are the degrees of freedom for this test?

3

If the coefficient of determination is .12 and SSY = 225, then what is the sum of squares regression for an analysis of regression?

IT IS NOT: 27

The equation for the standardized regression equation is

IT IS NOT: equation with Y MAYBE: equation with Zy

Which of the following would not be reported for a correlation?

the critical values for each test

A researcher measures the extent to which the speed at which people eat (in minutes) predicts calorie intake (in kilocalories). Which factor is the predictor variable in this example?

the speed at which people eat

A researcher reports the following results for a chi-square test for independence: c2 (1) = 5.39, p < .05 (V = .22). How many groups were observed?

IT IS NOT: 3

Which of the following is not needed to compute the y-intercept using the method of least squares?

IT IS NOT: My MAYBE: the slope

The value of b1 and b2 are referred to as

IT IS NOT: standardized beta coefficients MAYBE: unstandardized beta coefficients

The denominator of the correlation coefficient measures the extent to which two variables

vary independently