# Scatterplots and correlation Notes.docx - STAT 101 Module...

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STAT 101 - Module One Page 1 of 11 Scatterplots and Correlation Review: Explanatory and Response Variables So remember from previous discussions, when we are looking at a relationship between two variables we assign them the roles of explanatory and response variable. We looked at a relationship between a categorical variable and a quantitative variable. Now, we will look at the relationship between two quantitative variables. For two quantitative variables we have: Response: Variable of interest (y) Explanatory: Helps explain the response (x) So now, let’s take a moment to run through some examples. Label which variable is the explanatory variable and which variable is the response in the following scenarios. 1. ACT composite score and freshman GPA Explanatory Variable: ACT Response Variable: GPA 2. Physical Response times and sleep deprivation Explanatory Variable: Sleep deprivation Response Variable: Response times 3. Height of Corn stalk and fertilizer type Explanatory Variable: Fertilizer type Response Variable: height of corn stalk 4. Number of cigarettes smoked per day and life expectancy Explanatory Variable: Number of cigarettes per day Response Variable: Life expectancy Scatterplots A scatterplot is used to display the relationship between two quantitative variables. The explanatory variable is put on the x-axis and the response variable is on the y-axis . We place a dot in the xy-plane corresponding the the pair (x,y). 1
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