st: A quick question

["Albert Newton" <lacneo@gmail.com>]

Hi folks,

   I have two varibles: weight and height of respondents in 1989.

weight1998      float  %9.0g
height1998      float  %9.0g

I want to create a new variable:

gen BMI = weight1998/(height1998^2)

My little problem is that:  BMI takes strange values if weight1998 is
missing.  Could anyone tell me why?  Thanks a lot!

height1998	weight1998	BMI1989
1.5748                  290                        53.04115
1.4732                  256                        53.50351
1.5494                  285                        53.84973
1.5494                  306                        57.8176
1.6764                  375                        60.52597
1.905                   .                          124.4902
1.778                   .                          142.9097
1.778                   .                          142.9097
1.6764                  .                          160.757
1.6764                  .                          160.757
1.6764                  .                          160.757



Albert

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