# Data Variables And Correlations – Final Exam Statistics

### Data Variables And Correlations, Negative Correlation Means, Grade Point Average

The key terms in these Statistic chapters include Date Variables And Correlations, Negative Correlation Means, Variables, Grade Point Average, Data, Positive Correlation, Pearson Correlation, Spearman Correlation, Dichotomous Variables. Final Exam Statistic.

The scatter plot for a set of X and Y values shows the data points clustered in a nearly perfect circle. For these data, what is the most likely value for the Pearson correlation?

either positive or negative near 0

What is indicated by a positive value for a correlation?

increases in X tend to accompanied by increases in Y

What would the scatter plot show for data that produce a Pearson correlation of r = +0.88?

points clustered close to a line that slopes up to the right

Which of the following Pearson correlations shows the greatest strength or consistency of relationship?

##### -0.90

fr = -0.70

The results from a research study indicate that adolescents who watch more violent content on television also tend to engage in more violent behavior than their peers. The correlation between amount of TV violent content and amount of violent behavior is an example of ______.

a positive correlation

A researcher measures IQ and weight for a group of college students. What kind of correlation is likely to be obtained for these two variables?

a correlation near zero

The scatter plot for a set of X and Y values shows the data points clustered in a nearly perfect circle. For these data, what is the most likely value for the Pearson correlation?

either positive or negative near 0

What is indicated by a positive value for a correlation?

increases in X tend to accompanied by increases in Y

What would the scatter plot show for data that produce a Pearson correlation of r = +0.88?

points clustered close to a line that slopes up to the right

Which of the following Pearson correlations shows the greatest strength or consistency of relationship?

##### -0.90

For which of the following Pearson correlations would the data points be clustered most closely around a straight line?
r = -0.70

A researcher measures driving distance from college and weekly cost of gas for a group of commuting college students. What kind of correlation is likely to be obtained for these two variables?

a positive correlation

A researcher records the odometer reading and price for a group of used Hondas. What kind of correlation is likely to be obtained for these two variables?

negative correlation

A negative correlation means that decreases in the X variable tend to be accompanied by decreases in the Y variable.

False

Suppose that there is a correlation of r = 0.41 between the amount of time that each student reports studying for an exam and the student’s grade on the exam. This correlation would mean that there is a tendency for people who study more to get better grades.

True

What values are specified by the null hypothesis for the chi-square test for goodness of fit?

Proportions for the entire population

What happens to the critical value for a chi-square test if the size of the sample is increased?

The critical value depends on the number of categories, not the sample size

What happens to the shape of the chi-square distribution as the df value increases?

The mode (highest point) of the distribution moves to the right

If the value of the Pearson correlation is r = +1.00 or -1.00, then all data points in a scatter plot fit perfection on a straight line.

##### True

A Pearson correlation of r = +0.90 indicates that the data points are clustered close to a line that slopes down to the right.

True

If you measured hearing acuity and age for a group of people who are 50 to 90 years old, you should obtain a positive correlation between the two variables.

False

Suppose that there is a correlation of r = 0.41 between the amount of time that each student reports studying for an exam and the student’s grade on the exam. This correlation would mean that there is a tendency for people who study more to get better grades.

True

What is indicated by a Pearson correlation of r = +1.00 between X and Y?

each time X increases, there is a perfectly predictable increase in Y

One or two extreme data points can have a dramatic effect on the size of the correlation.

True

A researcher finds a significant correlation between the amount of time spent watching television and blood pressure for a sample of 40-year old men. This means that watching more television causes high blood pressure

##### False

Data Variables And Correlations

For a two-tailed hypothesis test evaluating a Pearson correlation, what is stated by the null hypothesis?

the population correlation is zero

As the sample size gets larger, what happens to the size of the correlation that is needed for significance?

it gets smaller

For a two-tailed hypothesis test evaluating the significance of a correlation, the null hypothesis states that the sample correlation is zero

False

What correlation is obtained when the Pearson correlation is computed for data that have been converted to ranks?

the Spearman correlation

Under what circumstances is the phi-coefficient used?

when both X and Y are dichotomous variables

Which correlation should be used to measure the relationship between gender and grade point average for a group of college students?

Point-biserial correlation

For a group of graduating college seniors, a researcher records each student’s rank in his/her high school graduating class and the student’s rank in the college graduating class. Which correlation should be used to measure the relationship between these two variables?

Spearman correlation

The phi-coefficient is used to measure relationships for data that would also be appropriate for an independent-measures t test.

##### False

The phi-coefficient is the correct correlation to use when both X and Y are dichotomous variables.

True

If people are classified by age (over 30/under 30) and by political affiliation (Democrat/Republican), then the point-biserial correlation would be the proper technique to measure the relationship between the two variables.

False

What happens to the shape of the chi-square distribution as the df value increases?

The mode (highest point) of the distribution moves to the right

What conclusion is appropriate if a chi-square test produces a chi-square statistic near zero?

There is a good fit between the sample data and the null hypothesis

The chi-square test for goodness of fit evaluates

the shape or proportions for a population distribution

The scatter plot for a set of X and Y values shows the data points clustered in a nearly perfect circle. For these data, what is the most likely value for the Pearson correlation?

either positive or negative near 0

What is indicated by a positive value for a correlation?

increases in X tend to accompanied by increases in Y

The scatter plot for a set of X and Y values shows the data points clustered in a nearly perfect circle. For these data, what is the most likely value for the Pearson correlation?

either positive or negative near 0

What would the scatter plot show for data that produce a Pearson correlation of r = +0.88?

points clustered close to a line that slopes up to the right

Which of the following Pearson correlations shows the greatest strength or consistency of relationship?

##### -0.90

For which of the following Pearson correlations would the data points be clustered most closely around a straight line?
r = -0.70

The phi-coefficient is the correct correlation to use when both X and Y are dichotomous variables.

True

Suppose that there is a correlation of r = 0.41 between the amount of time that each student reports studying for an exam and the student’s grade on the exam. This correlation would mean that there is a tendency for people who study more to get better grades.

True

A researcher measures IQ and weight for a group of college students. What kind of correlation is likely to be obtained for these two variables?

a correlation near zero

Data

If the value of the Pearson correlation is r = +1.00 or -1.00, then all data points in a scatter plot fit perfection on a straight line.

True

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