EXERCISE 2 - ANSWER

Do people with years of schooling at or above the median level report a higher age at first sexual intercourse than those who report years of schooling below the median level, and if so, by how much?

The variables we need to answer this question have already been used in this module so there is probably no need to look them up. We will use the variables educ and sexage.  To answer this question we need to proceed in steps. The first step is to figure out the median level of years of schooling. To do this you could type:

sum educ, detail

                  number of years in school
-------------------------------------------------------------
      Percentiles      Smallest
 1%            1              1
 5%            3              1
10%            4              1       Obs                3448
25%            6              1       Sum of Wgt.        3448

50%            8                      Mean           8.078016
                        Largest       Std. Dev.      3.366933
75%           10             22
90%           12             22       Variance       11.33624
95%           14             23       Skewness       .5019617
99%           17             25       Kurtosis       3.849107

From the output above we learn that the median years of schooling is 8 years.  The second step is to investigate the mean of sexage for respondents reporting years of school greater than or equal to the median, to do this you could use the following syntax:
 

means sexage if educ >= 8 & educ ~= .

 

    Variable |    Type        Obs        Mean       [95% Conf. Interval]
-------------+----------------------------------------------------------
      sexage | Arithmetic    1242    18.35105         18.1968   18.50529 
             |  Geometric    1242     18.1583        18.01294   18.30483 
             |   Harmonic    1242    17.96953        17.82202    18.1195 
------------------------------------------------------------------------

The third step is to investigate the mean of sexage for respondents reporting years of school less than the median, to do this you could use the following syntax:

 

 

means sexage if educ < 8 & educ ~= .

 

    Variable |    Type        Obs        Mean       [95% Conf. Interval]
-------------+----------------------------------------------------------
      sexage | Arithmetic     765    18.64706        18.41784   18.87628 
             |  Geometric     765    18.38682        18.17118   18.60502 
             |   Harmonic     765    18.13772        17.92667   18.35379 
------------------------------------------------------------------------

 

We see that the average age at first sexual intercourse among the first group is 18.35, while that of the second group is 18.64.  Given these findings, it seems there is virtually no difference in the average age at first sexual intercourse between these two groups.

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