Stat 539: Biostatistics Methods II
  Homework assignment 7, due Thursday March 30 

      Recall the data from the second HW, given below:

      The following data were collected from 48 women who were at least
      40 years old when they gave birth to their first child. The data
      concern the gestation period of that pregnancy, and related 
      variables on the child and mother.

      The columns are, from left to right: 

      1) ID 
      2) The child's gestation period, in weeks
      3) Sex of the child (0=Male, 1=Female)
      4) Birth Weight of child, in grams
      5) Number of cigarettes smoked per day (on average) by the mother
      6) Height of mother in cm
      7) Weight of mother in kilograms at first prenatal visit
      8) Weight of mother in kilograms at final prenatal visit

       The goal of the analysis is to determine whether there is an effect 
       of child's sex on the birth weight, after adjusting for other 
       features that might impact birth weight. Devise an analysis to 
       answer this question.  Treat smoking as a categorical variable as in 
       the CHDS data, but just define two groups (NS/S).

       Now you have two categorical variables (although your main interest is 
       in child's sex), and several covariates.  This then is a two-way ANOVA
       with covariates, so you need to worry about interaction between the Sex
       and Smoking variables (maybe smoking affects the weight of one gender 
       differently from another).  Any such effects need to be adjusted for the 
       covariates.

       If you find a significant sex effect then quantify the direction and 
       size of the effect (i.e. present and interpret appropriate mean 
       differences based on the selected model). Make sure to clearly 
       summarize your findings.


     DATA
     ----
        1  36  0  3300  0   160.0  67.3  82.7
        2  38  0  3300  60  167.6  52.7  76.0
        3  38  0  4100  20  167.6  64.2  79.6
        4  38  1  2900  10  163.9  72.7  95.8
        5  39  0  2820  0   161.3  50.0  63.3
        6  39  0  3040  0   158.8  49.1  61.5
        7  39  0  4120  0   160.0  57.7  73.5
        8  39  0  4200  0   174.0  68.0  86.8
        9  39  1  3100  0   171.5  67.3  85.6
       10  39  1  3330  0   160.0  74.0  90.5
       11  39  1  3410  0   165.1  55.9  70.7
       12  39  1  3420  0   162.6  52.3  66.0
       13  40  0  2450  20  167.6  61.4  72.5
       14  40  0  2885  0   167.7  60.0  78.6
       15  40  0  3235  0   170.2  50.0  65.5
       16  40  0  3320  0   165.1  63.6  80.2
       17  40  0  3600  0   165.1  53.2  68.7
       18  40  0  3720  0   165.0  57.7  74.4
       19  40  0  3720  0   172.7  61.4  80.0
       20  40  0  3820  0   175.3  60.8  78.1
       21  40  0  3840  0   167.0  60.5  83.9
       22  40  0  3880  0   156.2  57.3  73.7
       23  40  0  3960  0   157.5  52.7  68.2
       24  40  0  4465  0   157.5  51.4  66.4
       25  40  1  2980  0   160.0  47.7  55.2
       26  40  1  3040  0   162.0  49.0  60.3
       27  40  1  3060  20  157.5  61.0  75.0
       28  40  1  3100  0   170.2  55.5  64.6
       29  40  1  3120  0   160.3  56.8  75.4
       30  40  1  3205  0   172.7  58.2  75.5
       31  40  1  3220  0   170.0  64.6  86.0
       32  40  1  4100  40  167.0  67.0  85.0
       33  41  0  3100  0   168.9  61.4  69.2
       34  41  0  3720  0   170.2  57.7  67.7
       35  41  0  3720  20  170.2  57.7  80.5
       36  41  0  3900  0   167.0  68.0  85.4
       37  41  0  3990  0   165.1  52.3  71.2
       38  41  0  4050  0   167.6  61.0  78.5
       39  41  0  4080  0   162.6  59.1  83.1
       40  41  0  4100  0   165.1  60.5  86.5
       41  41  0  4460  20  165.1  56.8  88.0
       42  41  0  5220  0   157.5  56.8  68.2
       43  41  1  3300  40  162.6  74.1  89.7
       44  41  1  3400  0   172.7  71.4  87.8
       45  41  1  4000  0   165.1  90.0  100.8
       46  41  1  4030  0   166.0  63.0  95.3
       47  43  1  3220  0   166.4  60.9  72.0
       48  43  1  4270  0   162.6  54.5  70.3