Exam 3: Finding Relationships Among Variables

Suppose that the table shown below contains information technology (IT) investment as a percentage of total investment for eight countries during a recent decade. It also contains the average annual percentage change in employment during this decade. Explain how these data shed light on the question of whether IT investment creates or costs jobs. (Hint: Use the data to construct a scatterplot.)

The Filters field of a pivot table contains the data that you want summarized.

A sample of 30 schools produced the pivot table shown below for the average percentage of students graduating from high school. Use this table to determine how the type of school (public or Catholic) that students attend affects their chance of graduating from high school.

A trend line on a scatterplot is a line or a curve that "fits" the scatter as well as possible.

If the sample is a good representation of the population, what percentage of those who spent the weekend studying should we expect to do poorly on the final exam?

We can infer that there is a strong relationship between two numerical variables when:

The limitation of covariance as a descriptive measure of association is that it

If the correlation of variables is close to 0, then we expect to see:

Side-by-side box plots allow you to quickly see how two or more categories of a numerical variable compare.

Data has been collected on store size in square feet and profit per square foot, yielding the following observations: How is the value of the correlation affected in each of the following cases? a) Each X value is multiplied by 4. b) Each X value is switched with the corresponding Y value. c) Each X value is increased by 2.

An economic development researcher wants to understand the relationship between the average monthly expenditure on utilities for households in a particular middle-class neighborhood and each of the following household variables: family size, approximate location of the household within the neighborhood, and indication of whether those surveyed owned or rented their home, gross annual income of the first household wage earner, gross annual income of the second household wage earner (if applicable), size of the monthly home mortgage or rent payment, and the total indebtedness (excluding the value of a home mortgage) of the household. The correlation for each pairing of variables are shown in the table below: Table of correlations -Which of the variables have a positive linear relationship with the household's average monthly expenditure on utilities?

Tables used to display counts of a categorical variable are called:

Examples of comparison problems include:

Approximate the percentage of these Internet users who are in the 58-71 age group.

What is the average annual salary of the employed Internet users in this sample?

Suppose that the percentage of a country's population without health insurance coverage based on samples from all its regions for both 2016 and 2017 produced the following table of correlations. ​ ​ ​ What does the table for the two given sets of percentages tell you in this case?

If the standard deviations of X and Y are 15.5 and 10.8, respectively, and the covariance of X and Y is 128.8, then the correlation coefficient is approximately 0.77.

Correlation can be affected by the measurement scales applied to X and Y variables.

Approximate the percentage of these internet users who are women.

The scatterplot is a graphical technique used to indicate the relationship between two numerical variables.