Challenge 6 (Loops)

This challenge builds immediately on the loop you wrote in exercise 8. The goal is to put everything together in something closer to real work. For a list of variables, we will write loops to produce:

• A table of summary statistics
• A histogram saved to disk for each variable

The loop you wrote for exercise 8 should look something like:

* create a local of continuous variables
    local				vars yield_kg harvest_value_USD nitrogen_kg totcons_USD

* loop over each variable and print out the number of observations	
	foreach v of varlist `vars' {
		qui sum 			`v', detail
		local				N = r(N)
		display				`N'
	}

Within this loop, add a programming if statement that for variables stricly less than (<) 63,450 displays as text the following: “Skipping `v' (only `N' non-missing obs)”. Recall that after a programming if ... statement you need {} and it is inside these brackets where you put the text you want displayes if the statement is true.

Within this if loop, us continue to to tell Stata to move on to the next variable (this will have the effect of Stata moving onto the next variable without graphing variables with observations < 63450).

Outside of the if loop, tell Stata what to do when the if statement is not true. That is, draw a hist of the variable `v'. Label the title "Distribution of `v'" and x-axis label "`v'". Save the graph with a name that depends on the variable, e.g. hist_yield_kg.png.

In the end, you should have one loop inside another. The outside loop is the foreach loop above. The inside loop is the one that follows if .... The code for the hist goes inside the first loop but not inside the second. That second loop tells Stata what to do when the if statement is true. If the statement is not true, than Stata will automatically draw the hist