For Values (Loops)

In this exercise you will use forvalues to loop over survey waves and compute summary statistics.

1. Use tab to determine how many survey waves (wave) are in the data set. How many waves are in the data set?

2. Use a forvalues loop to summarize yield_kg separately for each wave. Your code should:
   • Loop over all integer values of wave observed in the data (for example, 1/3 if there are 3 waves).
   • For each wave:
     • Display a header line like "Wave 1".
     • Run summarize yield_kg if wave == ....

   Example structure (modify the range to match your data):

   forvalues w = 1/3 {
       display "------------------------"
       display "Summary for wave `w'"
       summarize yield_kg if wave == `w'
   }
   

   What is mean yield in each wave?

3. Extend your loop so that for each wave it also summarizes nitrogen_kg. What is mean nitrogren use in each wave?

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