Question

. . tabulate sex os2, row

+----------------+

| Key            |

|----------------|

|   frequency    |

| row percentage |

+----------------+

          os2

  sex |     0 (Mac) 1 (Win)|  Total

-----------+----------------------+----------

Female |      22          6 |        28

           |     78.57      21.43 |    100.00

-----------+----------------------+----------

Male |         5          9 |        14

           |     35.71      64.29 |    100.00

-----------+----------------------+----------

   Total |        27         15 |        42

           |     64.29      35.71 |    100.00

Compute the following measures of association between sex and preferring Windows and interpret each quantity:

a.) Risk Difference

b.) Relative Risk

c.) Odds Ratio

Answer 1

Our exposed group is preference of windows.

	Mac	Win	Total
Female	a=22	c=6	a+c=28
Male	b=5	d=9	b+d=14
Total	a+b=27	c+d=15	a+b+c+d=42

(a)

Risk Difference = =

RR = 0.4148

Women preferring mac over windows were greater than males preference of mac over windows by 41.48%.

(2)

Relative Risk = =

RR = 2.037

Female preference of mac over windows is 2.037times more than males.

(3)

Odds Ratio= =

OR = 6.6

Similar to relative risk ratio, for our data set the odds of women preferring mac over windows is 6.6times that of men.