In 1991, researchers conducted a study on brain size as measured by pixels in a magnetic resonance imagery (MRI) scan. The numbers are in hundreds of thousands of pixels. The data table provides the sizes of the brains and the gender.

a. Is the format of the data set stacked or unstacked?

b. Explain the coding. What do 1 and 0 represent?

c. If you answered “stacked” in part a, then unstack the data into two columns labeled Male and Female. If you answered “unstacked,” then stack the data into one column; choose an appropriate name for the stacked variable.

Brain Male

9.4 ..........1

9.5 ..........0

9.5 ..........1

9.5 ..........1

9.5 ..........0

9.7 ..........1

9.9 ..........0