Question 1

A correlational study would be used to determine if a relationship existed between rainfall levels and crime rates.

Accepted Answer

A correlational study is designed to determine if there is a relationship between two variables. In this case, the two variables are rainfall levels and crime rates.

Question 2

The fewer absences that students have,the higher their grade point average.This illustrates a negative relationship.

Accepted Answer

A negative relationship means that as one variable increases, the other variable decreases. In this case, as the number of absences decreases, the grade point average increases.

Question 3

If the mean on a test is 90 and the standard deviation is 10,a person with a z-score of -1.0 scored 110 on the test.

Accepted Answer

This is not possible. A z-score of -1.0 indicates a score that is one standard deviation below the mean (90-10=80). Therefore, a score of 110 is not possible with this z-score.

Question 4

If one calculates a correlation of -1.15,this coefficient of correlation indicates a strong negative relationship.

Accepted Answer

The correlation coefficient always falls between -1 and 1. It cannot be greater than or less than that. Therefore, a correlation coefficient of -1.15 is not possible and indicates an error in calculation or data input.

Question 5

A correlation of +1.00 or -1.00 means that 100 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 two measures, where all the data points fall on a straight line. In this case, knowing the value of one measure (X) completely determines the value of the other measure (Y), and therefore 100% of the variation in Y is accounted for by knowing X.

Question 6

The simplest way of visualizing a correlation is to construct a scatter diagram.

Accepted Answer

A scatter diagram is a graph used to display the relationship between two continuous variables. It is a simple way of visualizing the correlation between the two variables.

Question 7

Inferential statistics allow us to generalize from the behavior of small groups of participants to that of the larger groups they represent.

Accepted Answer

This statement is true. Inferential statistics allow us to make conclusions or predictions about a population based on a sample of participants.

Question 8

Direct measurement has shown such characteristics as height,memory span,and intelligence to be distributed approximately along a normal curve.

Accepted Answer

Direct measurement has indeed shown that certain characteristics are distributed along a normal curve, with most people falling within the average range and fewer people falling in the extremes (either high or low). This is known as the normal distribution or the bell curve.

Question 9

Correlations allow us to determine causation between two variables.

Accepted Answer

Correlation does not necessarily imply causation. Just because two variables are correlated does not mean that one causes the other. There could be other factors at play that influence both variables or the correlation could be purely coincidental.

Question 10

If higher environmental temperature is related to higher anger levels in people,then a positive relationship exists
between the environmental temperature and people's anger levels.

Accepted Answer

The statement says that there is a positive relationship between environmental temperature and people's anger levels, which means as one variable increases, so does the other. Therefore, the correct answer is A - true.

Question 11

Five hundred students out of the 4,000 students at Meridian Community College are surveyed regarding their views on extracurricular activities available on campus.These 500 students would be considered the population in this survey.

Accepted Answer

The answer of Five hundred students out of the 4,000...

Question 12

Often,two correlated measures are related as a result of the influence of a third variable.

Accepted Answer

This statement is true. A third variable can potentially affect the relationship and correlation between two other variables. This is known as a confounding variable.

Question 13

An important advantage of the standard deviation is that it can be used to "standardize" scores in a way that gives
them greater meaning.

Accepted Answer

Standard deviation can be used to standardize scores by calculating the z-score, which indicates how far a particular score is from the mean in terms of standard deviation units. This standardized score allows for meaningful comparisons between scores from different samples or populations.

Question 14

A bell-shaped distribution,with a large number of scores in the middle,tapering to very few extremely high and low scores is known as a negatively-skewed curve.

Accepted Answer

A bell-shaped distribution with a large number of scores in the middle and tapering at the extremes is known as a normal distribution. A negatively skewed curve has a long tail on the left side, indicating that there are more scores on the right side of the distribution.

Question 15

In order to determine how much two means must differ for this difference to be considered "real and not due to
chance," we must use a procedure known as percent variance.

Accepted Answer

This statement is incorrect. The procedure used to determine the significance of the difference between two means is hypothesis testing, not percent variance. Specifically, a statistical test such as a t-test or ANOVA is used to determine if the difference between the means is statistically significant.

Question 16

Results of an experiment that have a chance probability of .05 are usually regarded as statistically significant.

Accepted Answer

A chance probability of .05 (or lower) indicates that there is a low likelihood of obtaining the observed results by chance alone, and therefore the results are considered statistically significant.

Question 17

An effective way to make sure that a sample is representative is to use random selection.

Accepted Answer

Random selection ensures that each member of the population has an equal chance of being included in the sample, which helps to ensure that the sample is representative of the entire population.

Question 18

The index of how much a typical score differs from the mean of a group of scores is known as the Pearson r.

Accepted Answer

The index of how much a typical score differs from the mean of a group of scores is known as the standard deviation, not the Pearson r. The Pearson r is a measure of the strength and direction of a linear relationship between two variables.

Question 19

The relationship of the standard deviation to the normal curve makes it possible to compare groups of scores if they come from distributions that are approximately normal.

Accepted Answer

This is true. The normal curve is a probability distribution that is characterized by its mean and standard deviation. If a group of scores comes from a distribution that is approximately normal, then it is possible to use the standard deviation to make comparisons between groups, such as determining which group has a higher average score or which group has more variability in their scores.

Question 20

Ninety-five percent of all cases are found between a standard deviation of +2 and a standard deviation of -2 on a normal curve.

Accepted Answer

This statement is true according to the empirical rule or 68-95-99.7 rule of normal distribution which states that 68% of the data fall within one standard deviation of the mean, 95% of the data fall within two standard deviations, and 99.7% of the data fall within three standard deviations.

Quiz 79: Behavioral Statistics