Question 1

Glenda has determined that the correlation between the math screening test and her students' math grade is .40. What percent of the variation in math scores is accounted
For by knowing the students' scores on the screening test?

Accepted Answer

The coefficient of determination is found by squaring the correlation coefficient. So, 0.40 squared is 0.16, which means 16% of the variation in math scores is accounted for by the screening test scores.

Question 2

Which of the following would tell us the percentage of variance in one variable that can be accounted for by knowing the other variable?

Accepted Answer

The square of the correlation coefficient (r × r), also known as the coefficient of determination, tells us the percentage of variance in one variable that can be accounted for by knowing the other variable.

Question 3

It is important to keep in mind that correlation __________ causation.

Accepted Answer

Correlation does not prove causation. Just because two variables are correlated does not mean that one is causing the other. There could be other factors involved that are not measured or accounted for.

Question 4

In order to gain greater confidence that a cause-and-effect relationship exists,which of the following must be performed?

Accepted Answer

An experiment allows for manipulation of a variable and control of other variables, thereby allowing for a stronger determination of cause-and-effect relationships. Correlational studies and Pearson r only indicate a relationship between variables, but cannot establish causality. Case studies are based on a small, specific sample and may not be generalizable to a larger population, making it difficult to establish cause-and-effect relationships.

Question 5

If there is a .75 correlation between the hours that students devote to studying and their grades,

Accepted Answer

A correlation of .75 is a strong positive correlation, which suggests that there is a relationship between studying and grades. However, it is not safe to conclude that studying causes better grades. There may be other factors at play, such as motivation, interest, or intelligence. Therefore, option A is the best choice, as it acknowledges the possibility of a third variable that could account for the relationship.

Question 6

When we want to generalize from the behavior of a small group to a large group,we must rely on

Accepted Answer

Inferential statistics allows us to make inferences about a population based on a sample, which is necessary when we want to generalize from a small group to a large group. Descriptive statistics describe the characteristics of a sample or population, but do not make inferences about the larger group. Normative statistics involve comparing data to a standard or norm, which is not relevant in this scenario. There is no such thing as random statistics.

Question 7

If the correlation between anxiety and test scores is -.85,then we can safely conclude that

Accepted Answer

A correlation of -.85 indicates a strong negative relationship between anxiety and test scores, which means that as anxiety levels increase, test scores decrease. Therefore, choice D, "there is a negative relationship between anxiety and test scores," is the correct answer. Choices A and B are incorrect because they suggest a causal relationship between anxiety and test scores, which cannot be determined from a correlation. Choice C is incorrect because it suggests a positive relationship between the variables, which is not supported by a negative correlation coefficient.

Question 8

Wendy has determined that the correlation between her reading screening test and her students' reading grades is .30.What percent of the variation in reading scores is
Accounted for by knowing the students' scores on the screening test?

Accepted Answer

The coefficient of determination, which represents the percent of variation accounted for, is the square of the correlation coefficient. So, 0.30 squared is 0.09, or 9%.

Question 9

Correlations allow us to

Accepted Answer

Correlations can help us make predictions about the relationship between two variables, but they do not prove causation, demonstrate statistical significance, or generalize to large samples.

Question 10

A researcher studies the effects of a new therapy on a small group of depressed individuals in the hopes of generalizing these findings for use with all depressed people.This researcher is using __________ statistics.

Accepted Answer

Inferential statistics are used to generalize findings from a small sample to a larger population. This is what the researcher in question is attempting to do. Descriptive statistics summarize and describe the data collected from a sample, normative statistics compare individuals to a standard or norm, and random statistics involve randomization and probability calculations.

Question 11

Regarding correlations,which of the following statements is FALSE?

Accepted Answer

While a cause-and-effect relationship cannot be established solely on the basis of correlation, it is possible for two correlated variables to have a cause-and-effect relationship. However, additional evidence through experimentation is necessary to establish causality.

Question 12

The college admissions office has determined that the correlation between IQ scores and college grade point average is .50.What percent of the variation in college grades is
Accounted for by knowing IQ scores?

Accepted Answer

The square of the correlation coefficient (0.50) represents the proportion of variation in college grades that can be explained by IQ scores. So, 0.50^2 = 0.25 or 25%. Therefore, knowing IQ scores accounts for 25% of the variation in college grades. The correct answer is C.

Question 13

Experiments allow us to

Accepted Answer

Experiments are designed to determine causation between variables. By manipulating one variable (independent variable) and measuring the effect on another variable (dependent variable), we can determine if there is a cause-and-effect relationship between them.

Question 14

If there is a correlation of .78 between socioeconomic status and IQ score,which of the following statements is TRUE?

Accepted Answer

Correlation does not imply causation, so a third variable like education level could explain the relationship between socioeconomic status and IQ score.

Question 15

Regarding correlations,which of the following statements is FALSE?

Accepted Answer

Correlations can show a relationship between two variables, but they cannot establish causation. Other factors not accounted for in the correlation could also be contributing to the outcome. Therefore, it is a false statement to claim that correlations are the best way to establish causation.

Question 16

When using correlation,we CANNOT

Accepted Answer

Correlation only measures the strength and direction of the relationship between two variables. It cannot determine causation or whether one variable causes the other.

Question 17

If the correlation between the IQs of identical twins is .86,then,in any group of identical twins,what percent of the variation in the "Y" twins' IQs is accounted for by knowing
The IQs of their identical siblings (the "X's")?

Accepted Answer

The correlation coefficient squared (r^2) gives the proportion of variance in the Y variable (IQ of the second twin) accounted for by the X variable (IQ of the first twin). Therefore, r^2 = 0.86^2 = 0.7396 or 74% of the variation in the Y twins' IQs is accounted for by knowing the IQs of their identical siblings.

Question 18

Regarding two variables of interest,a correlation will tell us only the degree of

Accepted Answer

A correlation tells us the strength and direction of the relationship between two variables. It does not provide information on causation, influence, or variability between the variables.

Question 19

Inferential statistics are used for

Accepted Answer

Inferential statistics are used for all three purposes mentioned in the options: generalization from small samples, drawing conclusions, and decision making based on limited data. Therefore, the correct choice is D, i.e., "all of these."

Question 20

For a correlation of +1.00 or -1.00,what percent of the variation in the Y measure is accounted for by knowing the X measure?

Accepted Answer

A correlation of +1.00 or -1.00 indicates a perfect linear relationship between X and Y. This means that knowing the value of one variable completely determines the value of the other variable. Therefore, 100% of the variation in Y is accounted for by knowing X.

Quiz 19: Appendix A: Behavioral Statistics

Glenda has determined that the correlation between the math screening test and her students' math grade is .40. What percent of the variation in math scores is accounted For by knowing the students' scores on the screening test?

Which of the following would tell us the percentage of variance in one variable that can be accounted for by knowing the other variable?

It is important to keep in mind that correlation __________ causation.

In order to gain greater confidence that a cause-and-effect relationship exists,which of the following must be performed?

If there is a .75 correlation between the hours that students devote to studying and their grades,

When we want to generalize from the behavior of a small group to a large group,we must rely on

If the correlation between anxiety and test scores is -.85,then we can safely conclude that

Wendy has determined that the correlation between her reading screening test and her students' reading grades is .30.What percent of the variation in reading scores is Accounted for by knowing the students' scores on the screening test?

Correlations allow us to

A researcher studies the effects of a new therapy on a small group of depressed individuals in the hopes of generalizing these findings for use with all depressed people.This researcher is using __________ statistics.

Regarding correlations,which of the following statements is FALSE?

The college admissions office has determined that the correlation between IQ scores and college grade point average is .50.What percent of the variation in college grades is Accounted for by knowing IQ scores?

Experiments allow us to

If there is a correlation of .78 between socioeconomic status and IQ score,which of the following statements is TRUE?

Regarding correlations,which of the following statements is FALSE?

When using correlation,we CANNOT

If the correlation between the IQs of identical twins is .86,then,in any group of identical twins,what percent of the variation in the "Y" twins' IQs is accounted for by knowing The IQs of their identical siblings (the "X's") ?

Regarding two variables of interest,a correlation will tell us only the degree of

Inferential statistics are used for

For a correlation of +1.00 or -1.00,what percent of the variation in the Y measure is accounted for by knowing the X measure?