Question 1

After graphing your data, a pattern emerges in which the data points start out in the upper left of your plot and move toward the lower right. How would you describe this relationship?

Accepted Answer

This pattern indicates a negative correlation, where as one variable increases, the other decreases, hence the movement from upper left to lower right on the plot.

Question 2

What is the range of all possible values of the correlation coefficient?

Accepted Answer

The correlation coefficient measures the strength and direction of the linear relationship between two variables. It varies between -1 and 1, with -1 indicating a perfect negative correlation, 0 indicating no correlation, and 1 indicating a perfect positive correlation. Therefore, the range of all possible values for the correlation coefficient is from -1 to 1.

Question 3

The absolute value of the correlation coefficient refers to the ___________________ of the relationship.

Accepted Answer

The absolute value of the correlation coefficient is a measure of the strength of the relationship between two variables. It tells us how closely the variables are related, regardless of the direction of the relationship. A value of 1 indicates a perfect positive correlation, a value of -1 indicates a perfect negative correlation, and a value of 0 indicates no correlation.

Question 4

If you have a curvilinear relationship and the Pearson product moment correlation coefficient is close to zero, what can you conclude about the relationship between the variables?

Accepted Answer

The Pearson product moment correlation coefficient is used to measure the linear relationship between two variables. If the relationship between the variables is non-linear (curvilinear), the correlation coefficient will be close to zero even if there is a strong relationship between the variables. Therefore, we cannot conclude anything about the relationship between the variables based on this information.

Question 5

Malcolm is interested in the relationship between health and income. He hypothesizes that as household income increases; the long-term health of the individual also increases. This is an example of what type of hypothesized relationship?

Accepted Answer

The hypothesized relationship between household income and long-term health is a positive correlation, as Malcolm predicts that as household income increases, the long-term health of the individual will also increase.

Question 6

If you would like to examine the relationship between one dichotomous variable and one continuous variable, which type of correlation coefficient would you use?

Accepted Answer

The point biserial correlation coefficient is used to examine the relationship between a dichotomous variable and a continuous variable.

Question 7

As one variable increases, another variable also increases, is a statement about how the variables ___________________.

Accepted Answer

When two variables increase or decrease together, it is known as co-variation. Therefore, the best choice is "A) co-vary."

Question 8

After you plot your data points, there is no clear pattern formed. How would you describe this relationship?

Accepted Answer

When there is no clear pattern formed after plotting the data points, it indicates that there is a weak or no relationship between the variables being analyzed. This means that the values of one variable do not affect the values of the other variable.

Question 9

If you would like to examine the relationship between two categorical variables, which type of correlation coefficient would you use?

Accepted Answer

The Phi coefficient is used to examine the relationship between two categorical variables. The Point biserial coefficient is used when one variable is continuous and the other is dichotomous. Pearson product moment coefficient is used when both variables are continuous and normally distributed. Spearman rank coefficient is used when both variables are ordinal or non-normally distributed.

Question 10

A correlation is aimed at examining the __________________ between two concepts.

Accepted Answer

Correlation is used to examine the relationship between two variables or concepts. It does not measure the degree of differences or significance between them, but rather examines how they are related to each other.

Question 11

Mary performs an analysis of her volunteers and finds a -.74 correlation coefficient between the number of hours spent volunteers and the number of hours worked per week at a paid position. How would you assess the strength of this relationship?

Accepted Answer

The correlation coefficient of -.74 indicates a strong relationship, albeit inversely, meaning as the number of volunteer hours increases, the number of hours worked at a paid position tends to decrease, or vice versa.

Question 12

Becky finds that when the temperatures increase in the summer, less people show up for work at her organization. What type of relationship is she describing?

Accepted Answer

The answer of Becky finds that when the temperatures increase...

Question 13

If you run the Pearson product moment correlation on a set of data and you find a p-value of .02, what can you conclude about your hypothesis?

Accepted Answer

A p-value of .02 indicates that there is a statistically significant relationship between the variables. In hypothesis testing, if the p-value is less than the level of significance (usually .05), we reject the null hypothesis. Therefore, we should reject the null hypothesis and conclude that there is a relationship between the variables.

Question 14

The variables examined in a Person product moment correlation have what level of measurement?

Accepted Answer

The variables examined in a Person product moment correlation are both quantitative (continuous). Therefore, the level of measurement is continuous.

Question 15

When discussing correlation, what does 'r' stand for?

Accepted Answer

'r' stands for Pearson product moment correlation, which is a measure of the strength and direction of the linear relationship between two variables.

Question 16

After plotting your data on a graph and visually inspect it, you notice that there is a trend of data points starting the bottom left and going toward the upper right of you plot. How would you describe this relationship?

Accepted Answer

A trend of data points starting from the bottom left and going towards the upper right indicates a positive correlation, meaning as one variable increases, the other variable also increases.

Question 17

How would a perfect correlation (r=1) between two variables look on a scatterplot?

Accepted Answer

A perfect correlation (r=1) indicates a perfect positive linear relationship between two variables, meaning as one variable increases, the other variable increases at a constant rate. This relationship is represented on a scatterplot by data points that form a straight line from the lower left to the upper right.

Question 18

Mary performs an analysis of the relationship between volunteer age and amount of time spent volunteering. She finds that people volunteer a lot when they are younger, then they do not volunteer much during the middle portion of their life, and finally they volunteer a lot at the end of their life. How would you describe this type of relationship?

Accepted Answer

The relationship described is not a straight line, so it cannot be linear (D). Additionally, the fact that the amount of volunteering starts high, dips down, and then rises again is indicative of a curvilinear relationship (C). It is not described as weakly (A) or strongly (B) correlated.

Question 19

After performing a correlation analysis you find a correlation coefficient of .05. How would you assess the strength of the relationship?

Accepted Answer

The answer of After performing a correlation analysis you find...

Question 20

The sign of the correlation coefficient, positive or negative, refers to the __________________ of the relationship between the variables.

Accepted Answer

The sign of the correlation coefficient indicates the direction of the relationship between the variables. If the sign is positive, it means that the two variables move in the same direction. If the sign is negative, it means that the two variables move in opposite directions. The strength of the relationship is indicated by the absolute value of the correlation coefficient. The difference or latitude between the variables is not related to the sign of the correlation coefficient.

Quiz 11: Bivariate Correlation