Error while running ttest on a local

[Scott Rick]

Hi. I am trying to run a ttest on a local of multiple variables, but am getting the error "command ttest exited with an error when run using the entire sample". However, when I run the same command individually on variables in the local "vars" the command runs pererctly. Can someone please help me here. Thank you.

local myresults "Control = r(mu_1) Treated = r(mu_2) Diff = (r(mu_2)-r(mu_1)) pvalue = r(p)"

display "`myresults'"

#delimit ;
local vars pop_perkm2_2019  per60_2011 per85_2011 deathrate_2019 povertyperct ///
malariacase2018  denguecase2018  typoidtot_case2018 exphealth_percap1516 /// 
acuteresp_totcase2018 pneumoniatot_case2018  tb2018 influenzacase_2018 hepcases_2018  ///
diabetes20181k hypertension20181k htnanddm20181k cvds20181k ///
stroke20181k hepcases_20181k commoncancers20181k mentalillness_20111k ///
hospital_total1k hospital_beds_total1k icu_beds_total1k ventilators_total1k ///
;
#delimit cr
display "`vars'"


 
. foreach x of local vars {
  2.                 di "`x'"
  3.          table (command) (result),command(`myresults' : ttest `v'', by(stepone))                        
  4.          nformat(%6.2f  Control Treated Difference)                             
  5.         nformat(%6.0f  pvalue)
  6. }
pop_perkm2_2019
command ttest exited with an error when run using the entire sample
r(198);

end of do-file

[Nick Cox]

I don't follow what you want here but

 
 ttest `v''

might have one illegal quotation mark.

[Scott Rick]

Thanks, Nick Cox . I realised the extra quotation mark right after I posted here. However, even after removing it I continue to get the error below, and am unable to figure why. However, as seen below, this works perfectly well when the ttest is run individually for each variable. Since I have a large number of variables to test, I was hoping to loop it over a local of all variables (the code in #1). Would you know what's wrong here?

.. 
. foreach x of local vars {
  2.                 di "`x'"
  3.          table (command) (result),command(`myresults' : ttest `v', by(stepone))                         
  4.          nformat(%6.2f  Control Treated Difference)                             
  5.         nformat(%6.0f  pvalue)
  6. }
pop_perkm2_2019
command ttest exited with an error when run using the entire sample
r(100);




*with a single variable

 local myresults "Control = r(mu_1) Treated = r(mu_2) Diff = (r(mu_2)-r(mu_1)) pvalue = r(p)"

. 
. display "`myresults'"
Control = r(mu_1) Treated = r(mu_2) Diff = (r(mu_2)-r(mu_1)) pvalue = r(p)

. 
end of do-file

. table (command) (result),  command(`myresults' : ttest per60_2011 ,      by(stepone))

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------
                               |  Sample size n₁   Sample size n₂   Degrees of freedom   Confidence level   x₁ mean for population 1   x₂ mean for population 2   Two-sided p-value   Lower one-sided p-
> value   Upper one-sided p-value   Combined std. dev.   Standard deviation for first variable   Standard deviation for second variable   Std. error   t statistic
-------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------
ttest per60_2011 , by(stepone) |              18               15                   31                 95                   8.316667                   7.633333            .3219448                  .83
> 90276                  .1609724             1.942283                                2.029561                                  1.82978     .6788884      1.006547
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------

.

[Nick Cox]

You are looping over local macro x but not using it inside the loop. The local macro v is evidently not defined, so ttest has nothing to do.

As you've shown it the nformat() options are on separate command lines, which also looks wrong to me.

[Scott Rick]

Nick Cox: Thanks, Nick. That was ridiculous oversight on my part.

I am now trying to put the results into a table with the code below. However, the loop fails to append the individual ttests of each variable. As a result, my output table in word has just one row of the last variable "ventilators_total1k", as evidenced by the output under command "collect label list command, all" below. Could you please help me here? I tried moving the putdocx commands into the loop but that did not work for me. I assume I need to append the results from the table command before I do so, but am struggling to figure this out.

foreach x of local vars {
        di "`x'"
     table (command) (result),command(`myresults' : ttest `x', by(stepone))  ///
     nformat(%6.2f  Control Treated Difference) nformat(%6.2f  pvalue)
}

collect label list command, all

  Collection: Table
   Dimension: command
       Label: Command option index
Level labels:
           1  ttest ventilators_total1k, by(stepone)


*Formatting the table
collect style cell result[Control Treated Difference], nformat(%8.2f)
collect style cell result[pvalue], nformat(%6.4f)
collect style cell border_block, border(right, pattern(nil))
collect preview


*Export the table to Microsoft Word
putdocx clear
putdocx begin
putdocx paragraph, style(Title)

collect style putdocx, layout(autofitcontents)           ///
title("Table 1: Descriptive Statistics and Balance")

putdocx collect
putdocx save "${paperdir}\Tables\Table1.docx", replace

[Nick Cox]

You're making progress, but I stop here as pushing results programmatically into Word is not something I ever do.

You should get a better answer than that, but you would increase the chance of it by providing a proper reproducible data example (or rephrasing your code in terms of some standard Stata dataset).

Please as always follow https://www.statalist.org/forums/help#stata in specifying data.

[Scott Rick]

Thanks, Nick.