Question

Q8 Age of first sexual intercourse is important to examine when researching the HIV epidemic, especially in MSM (men who have sex with men) who are at high risk. The NYC Department of Health has asked us to examine whether there are race differences by age of first intercourse in our sample of 412 MSM. If men of specific race/ethnicity are more at risk than others then additional prevention services may need to be directed towards this group. Below and on the next page are the results of our Analysis of Variance. Please answer the questions on the next page. N I 1 black 2 latino 3 white 4 asian 5 mixed or other Mean 17.70 17.47 18.71 19.45 18.02 18.09 Standard Deviation 3.480 3.266 2.920 2.937 3.207 3.259 Total Sum of Sq. 190.514 ANOVA df Mean Square 4 47.628 Sig. .001 Between Groups | 4.644 (1) race (J) race Sig. Mean Difference Std. Error 430 1 black 471 .562 570 -1.89 232 - 1.010 - 1.751 -323 -232 - 1.242 -1.983 .556 1.010 1.242 .430 .440 2 latino 2 latino 3 white 4 asian 5 mixed or other 1 black 3 white 4 asian 5 mixed or other 1 black 2 latino 4 asian 5 mixed or other 1 black 2 latino 3 white 5 mixed or other 1 black 2 latino 3 white 4 asian .536 545 471 .440 .570 .577 .562 .983 204 .017 .980 .983 .040 .002 .846 204 .040 .691 .758 .017 .002 .691 .188 95% Confidence interval Lower Upper Bound Bound -95 1.41 -2.30 28 -3.29 -21 1.24 -1.41 .95 -2.45 -.04 -3.45 -51 -2.05 .94 - 28 2.30 .04 2.45 -2.30 .82 2.27 3.29 3.45 2.30 3.22 -1.24 1.89 - 94 2.05 -2.27 -3.22 36 3 white -741 .536 4 asian .687 1.751 1.983 .741 1.428 .323 556 .980 .570 654 .570 .545 .577 .654 5 mixed or other -.687 .846 .758 .188 90 -1.428

1. a) Do we accept the HA that there are differences in age of first intercourse? Explain and provide p-value.

2. b) If there are post hoc differences, please list between which races and provide p- values. (Please don’t list the same pairs twice).

3. c) Which race was at highest risk (the youngest age of first intercourse reported)? How do you know?

4. d) Which race was at lowest risk (the oldest age of first intercourse reported)? How do you know?

Answer 1

a)

Since p-value of F test (0.001) is less than 0.05 significance level, we accept HA and conclude that there is significant evidence that there are differences in age of first intercourse.

b)

All post hoc differences are significant for which the p-value is less than 0.05 significance level.

Black and Asian - P-value = 0.017

Latino and White - P-value = 0.04

Latino and Asian - P-value = 0.002

c)

The race was at highest risk is Latino because the lowest mean age of first intercourse reported is for Latino.

d)

The race was at lowest risk is Asian because the highest mean age of first intercourse reported is for Asian.