Stats Chapter 8
strength and direction of a relationship
A correlation coefficient provides two pieces of information about a relationship. They are the ______.
is a type of study that tests the hypothesis that variables are related
A correlational design ______.
more closely estimate the value of Y for a given X value
A regression equation allows you to ______.
ceiling effect
After a study, which assessed the anxiety of students before a Research Methods test, the researcher reports that all the students scored between 20 and 25 on the 25-point scale of anxiety. What problem might exist with the scale?
n-2
After computing a correlation, we compare our computed r value to the critical values for Pearson's r using ______ degrees of freedom.
impulsivity
Anne and Jack are examining variables related to self-control. Anne finds r = +.40 between percentage of salary saved and self-control while Jack finds r = .60 between impulsivity and self-control. Which variable is more strongly related to self-control?
the validity and reliability of measures
Correlation is the statistic used to assess ______.
better represent the everyday world where we do not manipulate or control events
Correlational designs can have greater external validity than experiments because correlational designs ______.
Multiple regression
Della wants to predict self-control scores using education level, impulsivity, and organizational skills as self-reported by students. She should compute ______.
0
If we find a perfect correlation, the standard error of the estimate would equal ______.
Y-intercept
In the regression equation, a = ______.
slope
In the regression equation, b = ______.
a third variable could be responsible for the relationship between our variables
One reason that correlational designs do not establish causality is ______.
when an experimental study would be unethical
One reason to use a correlational design is ______.
33% of the variability in academic honesty is accounted for by knowing its relationship with creativity
Shawn examines the relationship between creativity and academic honesty and finds the coefficient of determination equals .33 or r2 = - .33. This means that ______.
weaker; larger
The ______ the correlation, the ______ the standard error of the estimate.
standard of the estimate
The average error between predicted Y values and the actual Y values is called ______.
the predicted Y values (Y') for each X value in the sample range
The line of best fit represents ______.
correlation between a dichotomous and an interval/ratio variable
The point-biserial correlation coefficient (rpb) is used to analyze the ______.
Y' = bX + a
The regression equation is always represented by the formula ______.
Perfect positive relationship
The scatterplot above shows a ______.
strong positive correlation
The scatterplot above shows a ______.
a straight line
The scatterplot for a perfect correlation would show ______.
coefficient of determination
The statistic that describes the proportion of variability that is accounted for by knowing the relationship between two variables is the ______.
Pearson's r
The statistic used to determine whether a linear relationship exists between two interval/ratio variables is the ______.
how close the correlation coefficient is to the absolute value of 1.0; the sign of the coefficient
The strength of the relationship is evident from ______ and the direction of the relationship is evident from ______ in a correlation coefficient.
-1.0 and +1.0
The value of Pearson's r ranges between ______.
2
There are ______ regression equations for two correlated variables.
using measures that are valid and reliable
We can increase the power of a correlational study by ______.
df, criterion level, and type of alternative hypothesis (one- or two-tailed)
We select the critical value of r from the table of values based on the ______.
there will be too much error in our predicted values
We should not compute a regression equation if we do not find a significant correlation between two variables because ______.
greater than
We want our computed r value to be ______ the critical value listed in the table in order for it to be significant.
the data in pairs for each participant, with the X value in one column and the Y value in the next column on the same row
When entering data to analyze a correlation, you should be careful to enter ______.
negatively correlated
When two variables move in opposite directions (one increases while the other decreases), they are ______.
positively correlated
When two variables move in the same direction together (both increase or both decrease), they will be ______.
Ha: r ≠ 0
You believe that students anxiety is related to test scores in Research Methods. The alternative hypothesis stated in numerical terms would appear as ______.
Students anxiety will be negatively related to their test scores in Research Methods.
You believe that students anxiety is related to test scores in Research Methods. Which of the following represents a directional alternative hypothesis for your study?
0.16
You find a correlation between creativity and academic honesty of r = .40. The coefficient of determination for this relationship is ______.
find a significant correlation for two interval/ratio variables find a significant rpb
You should compute a linear regression equation when you ______.
point-biserial correlation coefficient
You want to examine the relationship between owning a house (yes - no) and income. You would compute a ______.