In this lab you analyzed a follow-up study. The original study involved 120 undergraduate volunteers. They conducted brain scans and looked at several different regions to see which regions showed an association with number of Facebook friends.

(a) Open the FirstFacebookBrainDensity.txt file and copy the data into the applet to create the scatterplot and calculate the least squares line.

Make a screen capture of the scatterplot (with the regression line displayed) and the equation for the regression and save into your report. Also make a screen capture of the Regression Table output and paste into your report.

(b) How does the regression line compare to the follow-up data for 40 subjects that you examined in this lab?


(c) From the Regression Table output, how do the standard error for the slope, t Ratio, and p-value for the slope for the original study to the follow-up data? Explain why these changes make sense based on what is different about between the two data sets.



Extra Credit: Why do you think this method of "look at a bunch of regions to see which are significant" is often criticized? (Hint: If I run lots of tests of significance using a 5% level of significance, how often will I reject the null hypothesis when I really shouldn't have? )



"Searching for significance" is poor statistical practice and the researchers actually used a "correction for multiple comparisons" as well as using the follow-up study that just focused on the regions identified in this pilot study.

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