Debugging (Problem Solving)

In this exercise you will practice systematic debugging using a deliberately broken .do file that works with plot_dataset.dta. Your goals are to:

Make the bug reproducible from a clean session.
Fix one bug at a time, always reading the error message.
Use Stata’s tools (describe, sum, list, help r(###), etc.) to understand what’s going on.
End with a clean, working script and a short reflection.

At the top of this exercise make sure you can reproduce errors from a clean session. To do this type

    clear              all
    do                 "$code/projectdo.do"

Run this script. Then copy the following broken code block directly after the line where you run the projectdo file.

******************************************************************
**# 1 - plot-level yield summaries
******************************************************************

* load data
    use             "$root/plot_dataset", clear

* create yield per hectare
    gen             yield_ha = harvestkg / plot_area_GPS

* summarize average yield for irrigated plots only, by main crop
    bys             main_crop: sum yield_ha if irrigated = 1, details

******************************************************************
**# 2 - save irrigated-only data by agro-ecological zone (aez)
******************************************************************

* get list of aezs
    levelsof        aez, local(agro_ecological_zone)

* loop over aezs and save a file for each
    foreach s of local agro_ecological_zone {

    * keep only irrigated plots for this aez
        keep        if agro_ecological_zone == s & irrigated == 1

    * save aez-specific file
        save        "$export/plot_yield_irr_s.dta"

    * reload data for next loop iteration
        use         "$root/plot_dataset.dta", clear
    }

There are multiple bugs in this code (file names, variable names, = vs ==, loop logic, options, and more). Do not fix anything yet. Run your assignment_7.do file from the top and let Stata stop at the first error.

For each bug you encounter:

Run your .do file from the top until Stata stops with an error.
Copy the error message and code in a comment below the offending line using the pattern (tabbed in twice):

*** ERROR HERE: r(111) type mismatch; harvestkg does not exist

Comment out the broken code and immediately below that *** comment decribing the error fix the bug. Then run the file from the top again to see the next error. Repeat this process until the entire script runs without errors. You should end up with a series of *** ERROR HERE: comments documenting each bug you found followed by your debugged code.

As you debug, remember to use Stata’s tools at appropriate points (do not use online help or an LLM).

describe
sum or sum, detail
list or browse
tab
help r(###) for the error codes you encounter
display of a macro (e.g., display "`s'") or returned result (e.g., display r(mean))

Each time you use one of these tools, add a short *** comment summarizing what you learned.

When you have completed this exercise you should have all the broken code commented out, followed by your comments regarding what the problem/bug was, and then a cleaned, working version of the buggy code block.