Assignment

This is a discussion question ! all instructions are below.

. Collect 50 or more paired quantitative data items. You may use a method similar to the Module 1 discussion to collect and enter data into StatCrunch. You will enter the explanatory variable (x-value) in column var1. Then, enter the response variable (y-value) in column var2.

a.) Using StatCrunch, compute the sample linear correlation coefficient, R. The Technology Step-by-Step box at the end of Section 4.1 (page 194) explains how to do so. Do not forget the video explanation in the Module Notes, if you need it.

b.) Using StatCrunch, find the least-squares regression line equation and plot the scatter diagram, along with the line. Page 207 (Technology Step-by-Step box) explains how to determine such a linear equation using StatCrunch. Please note: In order to plot the scatter diagram along with the line, before clicking Calculate in step 3 of page 207, scroll down to Graphs and make sure Fitted line plot is selected. Then click Calculate. Then click the right-arrow at the very bottom right hand side of the results page for the scatter diagram and regression line plot. For an example of the steps taken and what to expect, click here.

c.) Paste your scatter diagram (with the regression line drawn) and StatCrunch results in the discussion (by clicking on Options and then Copy. Use Ctrl V to paste it into the discussions).

Make sure your data set is large enough (50 items).

d.) Then, answer the following two questions:

    • What type of correlation do you observe between the two variables? For ideas, see Figure 4 on page 181 (Section 4.1).
    • Would you recommend using this linear model to make predictions about the y-value for a given x-value? Why or why not?

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