Looking at Data-Relationships Flashcards
2.1 Facebook friends. Do people who have more Facebook friends spend more time on Facebook? In an introductory statistics class of 32 students, there were 27 users of Facebook. Each of these students was asked to report how many Facebook friends they had and the average amount of time that they spent on Facebook per week.
a. Who are the cases for this study?
The cases are the Facebook users.
2.1 Facebook friends. Do people who have more Facebook friends spend more time on Facebook? In an introductory statistics class of 32 students, there were 27 users of Facebook. Each of these students was asked to report how many Facebook friends they had and the average amount of time that they spent on Facebook per week.
b. What are the variables?
The variables are the number of friends reported by each student and the average time spent on Facebook per week.
2.1 Facebook friends. Do people who have more Facebook friends spend more time on Facebook? In an introductory statistics class of 32 students, there were 27 users of Facebook. Each of these students was asked to report how many Facebook friends they had and the average amount of time that they spent on Facebook per week.
c. Are the variables quantitative or categorical? Explain your answer.
The variables are quantitative because they must be reported as numbers.
What word signifies that variables are related?
Associated
What does strength of association tell us?
It tells us how much one variable informs the other
Two variables measured on the same cases are _______ if knowing the value of one of the variables tells you something about the value of the other variable.
associated
Perceived stress is a _______, which involved combining the responses to 10 questions into a single variable.
composite scale
What does using a composite scale for categorical variables allow us to do?
It allows us to view it as quantitative.
2.2 Create a categorical variable from a quantitative variable. Consider the study described in Example 2.3. Suppose that we order the students based on the values of resources to cope from smallest to largest. Then, we define three resource groups: low resources, the first 32 students; medium resources, the next 33 students; and high resources, the remaining 32 students.
If we compare the perceived stress of the three resource groups, are we using resource group as a quantitative variable or as a categorical variable?
We are viewing it as quantitative.
A _______ variable measures an outcome of a study. An _______ variable explains or causes changes in the _______ variable.
response, explanatory, response
2.4 Stress and resources or resources and stress?
Consider the scenario described:
Stress is a common problem for college students. Searching for factors associated with stress may lead to strategies that will help students to relieve some of their stress. A recent study found that students who experienced greater stress had less access to resources that would help them to cope with their stress.1 The two variables involved in this relationship are perceived stress and resources to cope. The cases are the 97 students who were the subjects for this particular study.
Note that the variable, resources to cope, is constructed by summarizing the responses to 20 questions that include items measuring the skills that the student has developed to reduce stress.
Make an argument for treating stress as the explanatory variable and resources to cope as the response variable.
Stress is the explanatory variable because it is able to explain the impact that the response variable has.
Resources is the response variable because it answers the study’s question. It may also be thought that because students had more stress, the resources were less able to help them cope.
T or F
There must always be a response and an explanatory variable when relating two variables.
False
Explanatory variables are sometimes called _______ variables, and response variables are sometimes called _______ variables.
independent, dependent
Two variables measured on the same cases are _______ if knowing the values of one variable tells you something about the values of the other variable. If we think that one variable may explain or even cause changes in another variable, we call the first variable an _______ variable and the second variable a _______ variable.
associated, explanatory, response
2.2 Explanatory or response?
For each of the following scenarios, classify each of the pair of variables as explanatory or response or neither. Give reasons for your answers.
The quality rating of a laundry detergent and the price per load of the detergent.
E: quality
R: price
A higher quality product should be worth more money.
