Combine two variable to create one variable

[george spare]

Hello,
I need to combine these two variables, sdh ( depression) and thsuci (suicide), to create one variable. In sdh and thsuci, 1 indicates "No," and 2 " Indicates "Yes".


. tab sdh

Felt sad, |
depressed |
or hopeless | Freq. Percent Cum.
------------+-----------------------------------
No | 231 40.03 40.03
Yes | 346 59.97 100.00
------------+-----------------------------------
Total | 577 100.00

. tab thsuci

Thought to |
commit |
suicide | Freq. Percent Cum.
------------+-----------------------------------
No | 534 92.07 92.07
Yes | 46 7.93 100.00
------------+-----------------------------------
Total | 580 100.00


Thank you for your help.

[Ken Chui]

Where "yes" means both "suicide = yes" & "depress = yes", OR
"yes" means either one or both conditions are "yes"?

This may get you started, but do check for missings and how cases with missing were coded.

generate both = (sdh == 2 & thsuci == 2)
generate either = (sdh == 2 | thsuci == 2)

[Clyde Schechter]

First, 1 = yes, 2 = no coding is really inconvenient for use in Stata. Whatever you do with this data in Stata, you will be much better off recoding these as 1 = yes, 0 = no. Do that before you do anything else.

Once you have done that, you need to think about which of the many ways of combining the two variables you want. Just to give a few examples of the possibilities:

• A variable that is Yes if the patient responded Yes to both of the original variables, no otherwise.
• A variable that is Yes if the patient responded Yes to either of the original variables, no otherwise.
• A variable that is Yes if the patient responded Yes to depression and No to suicide, no otherwise.
• A variable that is Yes if the patient gave the same response to both of the original variables, no otherwise.
• A variable that is Yes if the patient gave opposite responses to the original variables, no otherwise.

And those possiblities are by no means exhaustive: there are 16 possibilities in all. You have to figure out what you want first. Once you have recoded the original variables to 1 = yes, 0 = no and made your decision, you will be able to do what you ask making use of Stata's logical and relational operators. Read -help operator- for details and examples.

Added: Crossed with #2.

[george spare]

Thank you for your response. I want to create a new variable that combines these two variables as 0 = no to depression and no to suicide and 1= yes to depression and yes to suicide.

[Ken Chui]

Thank you for your response. I want to create a new variable that combines these two variables as 0 = no to depression and no to suicide and 1= yes to depression and yes to suicide.

	Suicide Yes	Suicide No
Depression Yes	Code to 1	???
Depression No	???	Code to 0

How would you resolve the "???" in the table? Do you want to leave them as no value (missing)?

[george spare]

I think for depression No, and suicide, Yes = code to 0 and regarding Depression, Yes and suicide no = code to 1.

[Clyde Schechter]

If you go with what you say in #6, then you don't need any new variable: the depression variable is already exactly that.