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# Statistics : Mean, Variance, Correlation, Standard deviation

Subject: Mathematics    / Statistics
Question

MODULE 5 – SELF TEST

When interested in examining how one variable changes in relation to another, which of the following descriptive statistics would you want to use?
Mean
Variance
Correlation
Standard deviation
A correlation coefficient can range in value. Which of the following illustrates this range?
–.01 to .01
–1.0 to 1.0
–2.0 to 2.0
–3.0 to 3.0
If variables change in the same direction, what type of correlation is this called?
Positive correlation
Negative correlation
Positive causation
Negative causation
If variables change in the opposite direction, what type of correlation is this called?
Positive correlation
Negative correlation
Positive causation
Negative causation
The correlation between variable X and variable Y is represented by which of the following?
RA(xy)2
rxy
rx(y)
Rx/y
Which of the following represent the Excel function to be used when computing correlation coefficients?
CORREL(A:10; B:10)
CORREL(A:1-10; B:1-10)
CORREL(A1:A10, B1:B10)
CORREL(A10:B10)
What would you use to represent a correlation visually?
Histogram
Polygon
Line graph
Scatterplot
When data points group together in a cluster from the lower left-hand side of the xy axis to the upper right-hand side, what is this?
Negative slope
Positive slope
Negative intercept
Positive intercept
If the correlation between variables is .70, what percent of the variance is shared variance?
70%
30%
49%
51%
If the correlation between variables is .80, what is the coefficient of determination?
.20
.36
.64
.80
Which of the following correlations would be interpreted as a very strong relationship?
.80
.70
.60
.50
If you wanted to compute the correlation between two interval-level variables, which type of correlation should you use?
Point biserial
Phi
Spearman rank
Pearson
If you wanted to compute the correlation between two nominal-level variables, which type of correlation should you use?
Point biserial
Phi
Spearman rank
Pearson
If you wanted to compute the correlation between two ordinal-level variables, which type of correlation should you use?
Point biserial
Phi
Spearman rank
Pearson
If you wanted to compute the correlation between one nominal-level variable and one interval-level variable, which type of correlation should you use?
Point biserial
Phi
Spearman rank
Pearson
What is the most important characteristic of a correlation coefficient?
Sign
Absolute value
One-tailed
Two-tailed
Which of the following is an example of a research hypothesis for testing a correlation coefficient?
H1: rxy does not equal 0
H1: rxy equals 0
H0: rxy equals 0
H0: rxy does not equal 0
The level of risk or Type I error typically set for testing the level of significance of a correlation coefficient is which of the following?
.01
.50
.05
.10
Which of the following represents the test statistic for a correlation coefficient?
p
F
t
r
Which of the following is another use for correlation coefficients?
Testing mean differences
Testing causal relationships
Estimating reliability
Estimating power
If the correlation between two variables is .496, how much of the variance has not been accounted for?
24.6%
49.6%
50.4%
75.4%
What statistical technique is used to make predictions of future outcomes based on present data?
Analysis of variance
Repeated measures
Linear regression
Correlational analysis
Which of the following is used to illustrate the “best guess” as to the predicted Y variable score based on X?
Regression equation
Scatterplot
Standard error of the estimate
Regression line
What is another name for a regression line?
Line of best fit
Scatterplot line
Line graph
Line of the estimate
Which of the following symbols is associated with the independent variable in the regression equation?
X
Y
a
b
In regression, the criterion variable is also known as the ____________.
Independent variable
Dependent variable
Predictor variable
Correlated variable
A positive trend line is associated with what type of slope?
Negative slope
Direct slope
Positive slope
Nondirectional slope
Which of the following is like a standard deviation for all error scores in regression?
Error of the estimate
Error standard deviation
Standard error of estimate
Precision of error