Tricks in Stata

Anke Huss

Generating „automatic“ tables in a do-file

Why programming tables?

• It‘s much more writing in the do-file!

• BUT: once you have done it, the next one will be faster (copy & paste...)

• No more troubles with updates of your data

• No more copying mistakes, because Stata does it for you

Caerphilly castle

Used data: Caerphilly Prospective study (CAPS)

download at: www.blackwellpublishing.com/ essentialmedstats/datasets.htm

Basic idea

• Use the Stata data sheet for your table-to-be

illnMIdiabetes

%19.48 1.85

Stored results in r() and e()

• Use stored results usually from r-class: results after general commands

such as summarize are saved in r() and generally must be used before executing more commands. For an overview type:

return list

e-class: results from estimation commands (regress/logictic…) are saved in e() until the next model is fitted. Overview:

ereturn list

Steps

1. DESIGN TABLE FIRST: what do I want my table to look like?

2. generate a new variable for each column

3. replace cell with number of interest

4. use „outsheet“ to write your new variables in text/ excel file

Example 1

1. DESIGN FIRST: what do I want my table to look like? E.g.:

Illness %

Myocardial inf 19.48

diabetes 1.85

Example 1

2. Generate a new variable for each column

gen str illness = ““

gen percent =.

Illness %

Example 1

3. Replace cell with contents/ number of interest: first column

sort id

replace illness = “myocardial inf“ in 1

replace illness = “diabetes“ in 2

Illness %Myocardial inf

diabetes

Example 1

3. Replace cell with contents/ number of interest: second column

sum misort idreplace percent = r(mean)*100 in 1

sum diabetessort idreplace percent = r(mean)*100 in 2

format percent %9.2f

Illness %Myocardial inf 19.48

diabetes 1.85

Example 1

4. use „outsheet“ to write your new variables in text/ excel file

outsheet illness percent in 1/2 using textres/illns.txtFor further

*comment 1: this works only if you have set STATA to work in a specific STATA folder. Eg: cd "d:/Statistisches/automatic_tables/STATA„

*comment 2: you can also export as excel file (*.xls), but automatic import of new textfile lets graphics survive...

Example 1

*Alternative way to do the same: program a small loop:

gen str name = ""gen percent = .local i = 1foreach var of varlist mi diabetes {

replace name = “`var'“ in `i' sum `var' sort idreplace percent = r(mean)*100 in `i' local i = `i' + 1

}format percent %9.2f

Example 2

1. DESIGN TABLE FIRST:

Category percent

underweight 4.20

normal 32.03

overweight 51.29

obese 12.49

Example 2

2. Generate a new variable for each column

gen str category = ""

gen percent = .

Category percent

Example 2

3. Replace cell with contents/ number of interest: first column

sort id

replace category = "underweight" in 1

replace category = "normal" in 2

replace category = "overweight" in 3

replace category = "obese" in 4

Category percent

underweight

normal

Overweight

obese

Example 2

3. Replace cell with numbers: second column

ta bmicat, gen (bminew)*4 lines with percentages*4 variables with ending in numbers from 1 to 4 ---

LOOP!

forvalues i = 1/4 {sum bminew`i' sort idreplace percent = r(mean)*100 in `i'

}format percent %9.2f

Category percent

underweight 4.20

normal 32.03

Overweight 51.29

obese 12.49

Example 2

4. Outsheet

...same as in example 1

Less writing...

label list bmicatcapture drop percent category bminew*ta bmicat, gen (bminew)gen category =.gen percent = .forvalues i = 1/4 {

sum bminew`i' sort idreplace category = `i' in `i'replace percent = r(mean)*100 in `i'

}label values category bmicatformat percent %9.2f

Example 3

1. THINK FIRST: table after logistic reg.Myocardial infarction OR uci lci pval

Current smoking

Current smoking

(+ age)

Current smoking(+ age + bmi)

Example 3

2. Generate a new variable for each column

gen str currsmok = ""gen OR = .gen uci = .gen lci = .gen pval =.

Example 3

3. Replace cell with contents/ number of interest: first column

sort id

replace currentsm = "current smoking" in 1

replace currentsm = "current smoking + age" in 2

replace currentsm = "current smoking + age + bmi" in 3

Example 3

3. Replace cell with numbers: second columnlogistic mi cursmoke

sort idreplace OR = exp(_b[cursmoke]) in 1replace lci = exp(_b[cursmoke] - 1.96*_se[cursmoke]) in 1replace uci = exp(_b[cursmoke] + 1.96*_se[cursmoke]) in 1est store Alogistic miest store Blrtest A Bsort idreplace pval = r(p) in 1

... In lines 2 and 3

Example 3

4. outsheet

...as in example 1

Resulting table

Myocardial infarction OR uci lci pval

Current smoking 1.74 2.22 1.36 6.76e-06

Current smoking

(+ age)

1.67 2.18 1.28 0

Current smoking(+ age + bmi) 1.82 2.40 1.39 0

Other way to save results after estimation commands

• Use the statsby command: eg:

statsby "logistic mi diabetes smoking" _b _se, saving (D:\Statistisches\automatic_tables\STATA\data\caerphillystatsby.dta) replace

Statsby will collapse your dataset!

Store results in a new dataset and open the original file again. Rerun "statsby" with next variables and append data to first stored results.