Question 1

With a population of 100 children aged 7 through 14, we would expect ____ between height and reading vocabulary.

Accepted Answer

It is reasonable to expect some correlation between height and reading vocabulary, but it is unlikely that the correlation will be perfect (+1 or -1). Therefore, the best answer is B, since it acknowledges the possibility of a positive correlation, but also allows for a weaker, non-perfect correlation.

Question 2

A schedule for trains from Chicago to New Orleans in one column shows how far each stop on the route is from Chicago and in another column how far the same stops are from New Orleans.The correlation between the two columns is ____.

Accepted Answer

The correlation between the distances from Chicago and the distances from New Orleans for each stop is -1.00 because as the distance from Chicago increases, the distance from New Orleans decreases in a perfectly linear manner, indicating a perfect negative linear relationship.

Question 3

Exhibit 6-5: Indicate your choice of statistics for solving the following questions.
-Refer to Exhibit 6-5.We want to determine how a student's score compares with the scores of the rest of the class.

Accepted Answer

The z-score compares a student's score with the mean of the class and takes into account the standard deviation of the class. This provides a standardized score that allows for comparison between scores from different distributions.

Question 4

The difference between experimental group mean and control group mean divided by the standard deviation of the control group is called the

Accepted Answer

The formula described in the question is known as Cohen's d, which is a measure of effect size. Therefore, the correct answer is D. A is incorrect because the coefficient of determination is a measure used in regression analysis to determine how well the model fits the data. B and E are both incorrect because they are not actual measures used in statistics. C is incorrect because a z-score would involve subtracting the mean of the control group from an individual's score and dividing by the standard deviation of the control group.

Question 5

There is no relationship between variables when the correlation is ____.

Accepted Answer

A Pearson's product moment correlation of zero indicates that there is no relationship between the variables being measured.

Question 6

The mean of the squared deviation scores is called

Accepted Answer

The mean of the squared deviation scores is called variance.

Question 7

Which of these is not an advantage of percentile ranks?

Accepted Answer

Equal differences in percentile ranks do not have the same meaning at all points in the scale. For example, the difference between the 99th and 100th percentile is much greater than the difference between the 49th and 50th percentile.

Question 8

A Z-score of 51 is equal to a z-score of

Accepted Answer

The answer of A Z-score of 51 is equal to...

Question 9

If the difference between r and zero is doubled, the portion of Y variance associated with X variance is

Accepted Answer

The portion of Y variance associated with X variance is determined by the square of the correlation coefficient (r^2). If the difference between r and zero is doubled, then r becomes 2r, and (2r)^2 = 4r^2, which means the portion of variance is quadrupled.

Question 10

An investigator found ____ when correlating weight and sex drive among adult males of average height, which led him to conclude that a fat man is more likely to have high sex drive than a thin man.

Accepted Answer

A Pearson's product moment correlation between zero and +1.00 means that there is a positive correlation between weight and sex drive. However, it does not necessarily mean that being fat causes a higher sex drive. There could be other factors influencing this correlation, such as hormonal imbalances or different genetic traits. Therefore, it would be inaccurate to conclude that a fat man is more likely to have high sex drive than a thin man based solely on this correlation.

Question 11

Exhibit 6-5: Indicate your choice of statistics for solving the following questions.
-Refer to Exhibit 6-5.We want to know how well the class as a whole did on an examination.

Accepted Answer

The mean is the best choice for this question as it provides an overall average of the class's performance on the exam.

Question 12

A negative z-score is

Accepted Answer

A negative z-score means that the value is below the mean. Therefore, it can only be option B - always below the mean.

Question 13

The coefficient of determination reveals

Accepted Answer

The coefficient of determination (r^2) is a statistical measure that indicates the proportion of the variance in one variable that is predictable from the other variable. It shows the strength and direction of the relationship between two sets of data or variables. Therefore, it is most closely related to option E, which refers to the relationship between two sets of scores.

Question 14

A positive correlation between self-concept and reading achievement would indicate

Accepted Answer

A positive correlation between self-concept and reading achievement indicates that as one variable increases, so does the other. However, correlation does not imply causation, so we cannot conclude that one causes the other. Instead, we can predict that individuals with a low self-concept are likely to have lower reading achievement, based on the pattern of correlation.

Question 15

An investigator found strong evidence that elderly teachers and young teachers scored low on an aptitude test while middle-aged teachers scored high on this test.This is an example of

Accepted Answer

The scenario describes a curvilinear relationship between age of teachers and their scores on an aptitude test, where both the elderly and young teachers score low and the middle-aged teachers score high. This is not a case of a positive or negative correlation between the variables, nor is there a lack of relationship between the variables.

Question 16

Which of the following is not true of the normal curve?

Accepted Answer

The normal curve is a bell-shaped curve where the mean, median, and mode are all equal, hence B and C are true. The curve is also commonly used for estimating the percentage of scores above and below certain points, so option E is true. However, the normal curve suggests that small z-scores occur more often than large z-scores, so option D is not true.

Question 17

Multiplying all raw scores by two will

Accepted Answer

Multiplying all raw scores by a constant does not change the shape or position of the distribution, and therefore, it does not change the z-scores.

Question 18

Exhibit 6-5: Indicate your choice of statistics for solving the following questions.
-Refer to Exhibit 6-5.We want to know how spread out or heterogeneous the scores of a class are.

Accepted Answer

The standard deviation is the most appropriate statistic for measuring the spread or heterogeneity of scores in a class. It measures the average distance of scores from the mean, and therefore provides an indication of how widely scores are distributed around the central tendency. The mean and z-scores are measures of central tendency and are not useful for measuring variability, while Pearson's r is a measure of correlation between two variables and is not relevant for this question.

Question 19

The sign of the Pearson's r is related to the strength of the relationship.

Accepted Answer

The sign of Pearson's r indicates the direction of the relationship (positive or negative), not the strength. The strength is indicated by the magnitude of the coefficient, regardless of the sign.

Question 20

Exhibit 6-5: Indicate your choice of statistics for solving the following questions.
-Refer to Exhibit 6-5.We want to see how scores on this examination are related to scores on another examination.

Accepted Answer

Pearson's r is a correlation coefficient that measures the strength and direction of the linear relationship between two variables. It is the best choice for examining the relationship between scores on two different examinations. The mean, standard deviation, and z-score would not provide information about the relationship between the two variables.

Quiz 6: Descriptive Statistics