topic Re: How to create dummy variables - Categorical Variables in SAS Studio

How to create dummy variables - Categorical Variables

aalasady0 — Fri, 22 Sep 2017 05:28:51 GMT

Hello,

I'm trying to create dummy variables for companies in my data set. Unfortunately the output is all zeros.

This is my code below:

DATA WORK.IMPORT;
SET WORK.IMPORT;
IF COMPANY = COKE THEN COKED=1; ELSE COKED = 0;
IF COMPANY = KFC THEN KFCD=1; ELSE KFCD = 0;
IF COMPANY = PEPSI THEN PEPSID=1; ELSE PEPSID = 0;
IF COMPANY = NIKE THEN NIKED=1; ELSE NIKED = 0;
IF COMPANY = STARBUCKS THEN STARBUCKSD=1; ELSE STARBUCKSD = 0;
IF COMPANY = MCDONALD THEN MCDONALDD=1; ELSE MCDONALDD = 0;
IF COMPANY = HARDEES THEN HARDEESD=1; ELSE HARDEESD = 0;
RUN;

unfortunately the ouput for the dummy variables is all 0, so if the company is coke the output is also 0 and not 1

I don't understand what is wrong, please help.

Thanks

Re: How to create dummy variables - Categorical Variables

stat_sas — Fri, 22 Sep 2017 05:59:05 GMT

Hi,

Just put quotes.

IF COMPANY = "COKE" THEN COKED=1; ELSE COKED = 0;

Re: How to create dummy variables - Categorical Variables

ChrisBrooks — Fri, 22 Sep 2017 08:36:44 GMT

What @stat_sas says - basically what is happening in your code is that SAS assumes that COKE, NIKE etc are variables in the data set but once you add double quotes it takes them as string literals.

Re: How to create dummy variables - Categorical Variables

Loko — Fri, 22 Sep 2017 08:36:47 GMT

Hi,

When you say COMPANY = COKE actually you compare 2 variables - COMPANY and COKE. If the variablke COKE is missing in your dataset you will notice a NOTE within the log : Variable COKE is uninitialized.

The solution has already been provided by @stat_sas.

Re: How to create dummy variables - Categorical Variables

Astounding — Fri, 22 Sep 2017 10:08:55 GMT

Also note that once you add quotes, the exact spelling matters. "COKE" is different than "Coke". You may want to change the comparison:

if upcase(company) = "COKE" then CokeD=1; else CokeD=0;

Re: How to create dummy variables - Categorical Variables

ballardw — Fri, 22 Sep 2017 14:48:43 GMT

It might also help to describe how you are intending to use those dummy variables.

A large number of the SAS procedures will create internal dummies when needed so additional variables are not needed.