Program Code for Body Mass Index

Variables used to construct Body Mass Index (BMI_W1R)

IMONTH	Interview month
IDAY	Interview day
IYEAR	Interview year
H1GI1M	What is your birth date? [month]
H1GI1Y	What is your birth date? [year]
H1GH59A	What is your height [in feet]?
H1GH59B	What is your height [in inches]?
H1GH60	What is your weight?

Body Mass Index for Wave I was constructed for all respondents with valid age, height, and weight. Age is calculated at the time of interview using month and year of birth, with all respondents assigned 15 as the day of birth. Note that age is not rounded in this code.

Body Mass Index is calculated as follows:

height in meters = height in inches*.0254
weight in kilos = weight in pounds * .454
BMI = (kilos)/(meters²)

Body Mass Index (BMI) Construction Map
Wave	Feet Data Source	Inches Data Source (feet12)+inches ((feet12)+inches)²	Height - Height²	Meters - Meters²	Weight Data Source	Weight	BMI
W1 (R)	H1GH59A	H1GH59B	H_W1R H_SQW1R	M_W1R MSQ_W1R	H1GH60	W_W1R	BMI_W1R

/* Calculate Age at Wave 1    */
if h1gi1m = 96 then h1gi1m = .;
if h1gi1y = 96 then h1gi1y = .;
  intdt = mdy(imonth,iday,iyear);
  birthdt = mdy(h1gi1m,15,h1gi1y);
  age = int((intdt-birthdt)/365.25);

/* calculate bmi_w1r  Wave1 recalled BMI  */
if h1gh59a lt 95 and h1gh59b lt 95 then do;
  feetw1r = h1gh59a;
  inchw1r = h1gh59b;
  h_w1r = (12*feetw1r) + (inchw1r);
end;

attrib h_w1r   label = 'height in inches';

if h1gh60 lt 995 then do;
  w_w1r = h1gh60;
end;

attrib w_w1r   label = 'weight in pounds';

if h1gh59a lt 95 and h1gh59b lt 95 then do;
  if h1gh60 lt 995 then do;
    /* weight in kilos wave 1 recall  */
    k_w1r = w_w1r * .454;
    /* height in meters wave 1 recall */
    m_w1r = h_w1r * .0254;
    /* meters squared wave 1 recall   */
    msq_w1r = m_w1r * m_w1r;
    /* BMI wave 1 recall              */
    bmi_w1r = k_w1r/msq_w1r;
    attrib bmi_w1r label = "Body Mass Index Wave 1 Recall";

  end;
end;

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Program Code for Body Mass Index