1What does Pearson's correlation coefficient primarily measure?
Pearsonâs Correlation coefficient
Easy
A.The difference between two population means
B.The variation within a single variable
C.The ranks assigned to several treatments
D.The linear relationship between two variables
Correct Answer: The linear relationship between two variables
Explanation:
Pearson's correlation coefficient measures the strength and direction of the linear relationship between two quantitative variables.
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2What is the possible range of Pearson's correlation coefficient ?
Pearsonâs Correlation coefficient
Easy
A. to
B. to
C. to
D. to
Correct Answer: to
Explanation:
Pearson's correlation coefficient always lies in the interval .
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3What does a Pearson correlation coefficient of indicate?
Pearsonâs Correlation coefficient
Easy
A.A weak positive linear relationship
B.A perfect positive linear relationship
C.No relationship between the variables
D.A perfect negative linear relationship
Correct Answer: A perfect negative linear relationship
Explanation:
A value of indicates that the variables have a perfect negative linear relationship.
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4Spearman's rank correlation coefficient is most suitable for data expressed as what?
Spearmanâs Rank correlation coefficient
Easy
A.Residuals
B.Frequencies
C.Variances
D.Ranks
Correct Answer: Ranks
Explanation:
Spearman's coefficient measures association using the ranks of observations.
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5Which symbol is commonly used for Spearman's rank correlation coefficient?
Spearmanâs Rank correlation coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Spearman's rank correlation coefficient is commonly denoted by or .
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6Which formula gives Spearman's rank correlation coefficient when there are no tied ranks?
Spearmanâs Rank correlation coefficient
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
For untied ranks, is the difference between paired ranks and is the number of pairs.
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7What is the main purpose of regression analysis?
Regression Concepts
Easy
A.To calculate only the sample size
B.To arrange observations into ranks
C.To compare only population variances
D.To predict one variable from another
Correct Answer: To predict one variable from another
Explanation:
Regression analysis models relationships and can predict a dependent variable using one or more independent variables.
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8In regression analysis, what is the variable being predicted called?
Regression Concepts
Easy
A.Dependent variable
B.Independent variable
C.Ranking variable
D.Control variable
Correct Answer: Dependent variable
Explanation:
The dependent variable is the outcome that the regression model aims to explain or predict.
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9In the simple regression equation , what does represent?
Regression Concepts
Easy
A.The regression slope
B.The sample mean
C.The error variance
D.The vertical intercept
Correct Answer: The regression slope
Explanation:
The coefficient is the slope, representing the expected change in for a one-unit increase in .
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10How many regression lines are generally associated with two variables and ?
Regression lines
Easy
A.Four
B.Three
C.One
D.Two
Correct Answer: Two
Explanation:
There is one regression line of on and another regression line of on .
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11Through which point do both regression lines pass?
Regression lines
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Both regression lines pass through the point formed by the two sample means, .
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12Which regression line is used to predict when is known?
Regression lines
Easy
A.Regression line of on
B.Regression line of on
C.Regression line of on
D.Regression line of on
Correct Answer: Regression line of on
Explanation:
The regression line of on estimates values of from known values of .
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13How many independent variables are used in multiple regression?
Multiple correlation and regression
Easy
A.Two or more
B.Only one pair
C.Exactly one
D.Exactly zero
Correct Answer: Two or more
Explanation:
Multiple regression predicts a dependent variable using two or more independent variables.
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14What does a multiple correlation coefficient measure?
Multiple correlation and regression
Easy
A.Association between one outcome and several predictors
B.Frequency of values in grouped data
C.Variation among ranks within one sample
D.Difference between two independent sample means
Correct Answer: Association between one outcome and several predictors
Explanation:
The multiple correlation coefficient describes the strength of association between one dependent variable and a set of predictors.
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15Which equation represents a multiple linear regression model with two predictors?
Multiple correlation and regression
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
A two-predictor multiple regression model includes separate coefficients for and .
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16How many factors are studied in a one-way ANOVA?
Analysis of Variance: One-way classification
Easy
A.Four factors
B.One factor
C.Two factors
D.Three factors
Correct Answer: One factor
Explanation:
One-way ANOVA examines group differences based on a single factor or classification.
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17What is the usual null hypothesis in a one-way ANOVA?
Analysis of Variance: One-way classification
Easy
A.All group means are equal
B.All group variances are zero
C.All observations are identical
D.All sample sizes are equal
Correct Answer: All group means are equal
Explanation:
The null hypothesis states that the population means of all groups are equal.
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18Which statistic is used to test significance in ANOVA?
Analysis of Variance: One-way classification
Easy
A.-statistic
B.Median
C.-score
D.Range
Correct Answer: -statistic
Explanation:
ANOVA uses the -statistic, which compares variation between groups with variation within groups.
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19How many factors are studied in a two-way ANOVA?
Analysis of Variance: Two-way classification
Easy
A.Two factors
B.Three factors
C.One factor
D.Four factors
Correct Answer: Two factors
Explanation:
Two-way ANOVA studies the effects of two factors on a dependent variable.
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20What can a two-way ANOVA examine in addition to the main effects of two factors?
Analysis of Variance: Two-way classification
Easy
A.The median of each observation
B.The correlation of each factor
C.The ranks of all responses
D.The interaction between the factors
Correct Answer: The interaction between the factors
Explanation:
A two-way ANOVA can test whether the effect of one factor depends on the level of the other factor.
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21The covariance between and is , while their standard deviations are and , respectively. What is Pearson's correlation coefficient?
Pearsonâs Correlation coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using , we get .
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22The correlation between and is . If and , what is the correlation between and ?
Pearsonâs Correlation coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
A positive transformation of preserves the sign, while multiplication of by a negative value reverses it. Thus, the new correlation is .
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23For five observations, and . What is Pearson's correlation coefficient?
Pearsonâs Correlation coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using deviations from the means, and . Hence, .
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24Two judges rank six participants. If the sum of squared rank differences is , what is Spearman's rank correlation coefficient?
Spearmanâs Rank correlation coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using , we obtain .
Incorrect! Try again.
25Two rankings of five items are identical except that one pair of adjacent items is interchanged. What is Spearman's rank correlation coefficient?
Spearmanâs Rank correlation coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The swapped items each have a rank difference of , so . Thus, .
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26Five students are ranked in exactly reverse order by two examiners. What is Spearman's rank correlation coefficient?
Spearmanâs Rank correlation coefficient
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Exactly reversed rankings represent a perfect negative monotonic relationship, so Spearman's coefficient is .
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27In a simple linear regression, the correlation between the response and predictor is . What percentage of variation in the response is explained by the regression?
Regression Concepts
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The coefficient of determination is , so the regression explains of the variation.
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28A regression model predicts a student's score as , but the observed score is . What is the residual for this observation?
Regression Concepts
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
A residual is observed value minus predicted value. Therefore, .
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29The regression line of on is . What value of is predicted when ?
Regression lines
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Substituting gives .
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30The regression coefficients are and . If the correlation is positive, what is its value?
Regression lines
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , we get .
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31The two regression lines are and . What are the means ?
Regression lines
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Both regression lines pass through . Their common point is .
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32Given , , and , approximately what is the multiple correlation coefficient ?
Multiple correlation and regression
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using gives , so .
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33A fitted multiple regression equation is . What is the predicted value when and ?
Multiple correlation and regression
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Substitution gives .
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34If , , and , what is the partial correlation , approximately?
Multiple correlation and regression
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using gives .
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35A one-way ANOVA compares four treatments using observations in total. What are the between-treatment and within-treatment degrees of freedom?
Analysis of Variance: One-way classification
Medium
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
The degrees of freedom are between treatments and within treatments.
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36In a one-way ANOVA, the between-group sum of squares is with degrees of freedom, and the error sum of squares is with degrees of freedom. What is the statistic?
Analysis of Variance: One-way classification
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Here, and . Therefore, .
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37Three groups each contain four observations and have means , , and . If the grand mean is , what is the between-group sum of squares?
Analysis of Variance: One-way classification
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The sum is .
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38A two-way ANOVA without replication has row levels and column levels. What are the degrees of freedom for rows, columns, and error?
Analysis of Variance: Two-way classification
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The degrees of freedom are for rows, for columns, and for error.
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39In a two-way ANOVA without replication, the row sum of squares is with degrees of freedom, and the error sum of squares is with degrees of freedom. What is the row statistic?
Analysis of Variance: Two-way classification
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The row mean square is and the error mean square is . Thus, .
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40In a two-way ANOVA with replication, the interaction between factors and is statistically significant. What does this indicate?
Analysis of Variance: Two-way classification
Medium
A.Only factor has a statistically significant main effect
B.The effect of is identical at every level of
C.The effect of depends on the level of
D.Only factor has a statistically significant main effect
Correct Answer: The effect of depends on the level of
Explanation:
A significant interaction means that the effect of one factor changes across the levels of the other factor.
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41Two groups have the following summary statistics. Group 1: , , and within-group corrected sums . Group 2: , , and within-group corrected sums . What is the Pearson correlation after pooling all observations?
Pearsonâs Correlation coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Including between-group variation gives , , and . Hence .
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42A correlation matrix for variables has and . Which proposed value of can produce a valid positive semidefinite correlation matrix?
Pearsonâs Correlation coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Validity requires to lie in , approximately . Only lies in this interval.
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43Centered variables and satisfy , , and . If and , what is ?
Pearsonâs Correlation coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Here , , and . Thus .
Incorrect! Try again.
44For six paired observations, the values are and the corresponding values are . Using average ranks for ties, what is Spearman's rank correlation?
Spearmanâs Rank correlation coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The midrank vectors are and . Their Pearson correlation is .
Incorrect! Try again.
45For , the sum of squared differences between midranks is . Variable has tie groups of sizes and , while variable has one tie group of size . What is Spearman's rank correlation, rounded to three decimals?
Spearmanâs Rank correlation coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Tie-adjusted rank sums of squares are and . Their cross-product is , so .
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46The Spearman correlation between and is , with ties handled by average ranks. Variable is replaced by a strictly decreasing function of , while is replaced by a strictly increasing function of . What is the new Spearman correlation?
Spearmanâs Rank correlation coefficient
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
A strictly decreasing transformation reverses the ranks of , changing the correlation's sign. A strictly increasing transformation of preserves its ranks.
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47The population model is . Instead of , a researcher observes , where is independent of and . If the reliability ratio is , what is the population slope from regressing on ?
Regression Concepts
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Classical measurement error attenuates the slope by the reliability ratio: .
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48The true model is , with . If is omitted and , what is the population slope in the simple regression of on ?
Regression Concepts
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The omitted-variable formula gives .
Incorrect! Try again.
49Variables and are standardized and have correlation . Let be the residual from regressing on , and let be the residual from regressing on . What is ?
Regression Concepts
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Each residual has variance , while their covariance is . Their correlation is therefore .
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50The unordered pair of equations and represents the two regression lines of and . Which pair gives and the correlation coefficient ?
Regression lines
Hard
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
The lines intersect at . Their admissible regression coefficients are and , giving .
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51The regression lines are and . What is the ratio ?
Regression lines
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The regression coefficients have product , so . Since , the ratio is .
Incorrect! Try again.
52A dataset has , , , , and . Which pair gives the prediction of at and the prediction of at , respectively?
Regression lines
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The slopes are and . Substitution into the centered regression lines gives and .
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53Suppose , , and . What is the multiple correlation coefficient ?
Multiple correlation and regression
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
For two predictors, . Thus .
Incorrect! Try again.
54In a sample of observations, the partial correlation between and after controlling for and is . What is the statistic and its residual degrees of freedom for testing zero partial correlation?
Multiple correlation and regression
Hard
A. with df
B. with df
C. with df
D. with df
Correct Answer: with df
Explanation:
With two control variables, . Hence .
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55All variables are standardized, with , , and . Which values of result from regressing on and ?
Multiple correlation and regression
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Inverting the predictor correlation matrix gives and . Then .
Incorrect! Try again.
56Three groups have sizes , sample means , and within-group sums of squares . What is the one-way ANOVA statistic?
Analysis of Variance: One-way classification
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The grand mean is , giving and . Therefore .
Incorrect! Try again.
57A one-way ANOVA has groups, , total sum of squares , and . What is its statistic?
Analysis of Variance: One-way classification
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , and . Thus .
Incorrect! Try again.
58Four groups each contain observations and have means . The pooled error mean square is . For the contrast , what is the equivalent one-degree-of-freedom statistic?
Analysis of Variance: One-way classification
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The estimated contrast is , and its estimated variance is . Hence .
Incorrect! Try again.
59In a two-way ANOVA without replication, the data matrix is . What are the row and column statistics, respectively?
Analysis of Variance: Two-way classification
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The row, column, and error sums of squares are , , and . With , the statistics are and .
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60A balanced factorial experiment has replicates per cell. The cell means are , and the within-cell error sum of squares is . Which pair gives the interaction sum of squares and interaction statistic ?
Analysis of Variance: Two-way classification
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The four interaction deviations are , so . Since , .
Incorrect! Try again.
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