SPSS TUTORIALS
Quick Overview Contents
In SPSS, SELECT IF permanently removes
a selection of cases (rows) from your data.
- Example 1 - Selection for 1 Variable
- Example 2 - Selection for 2 Variables
- Example 3 - Selection for (Non) Missing Values
- Tip 1 - Inspect Selection Before Deletion
- Tip 2 - Use TEMPORARY
Summary
SELECT IF in SPSS basically means “delete all cases that don't satisfy one or more conditions”. Like so, select if(gender = 'female'). permanently deletes all cases whose gender is not female. Let's now walk through some real world examples using bank_clean.sav, partly shown below.
Example 1 - Selection for 1 Variable
Let's first delete all cases who don't have at least a Bachelor's degree. The syntax below:
- inspects the frequency distribution for education level;
- deletes unneeded cases;
- inspects the results.
set tnumbers both.
*Run minimal frequencies table.
frequencies educ.
*Select cases with a Bachelor's degree or higher. Delete all other cases.
select if(educ >= 4).
*Reinspect frequencies.
frequencies educ.
Result
As we see, our data now only contain cases having a Bachelor's, Master's or PhD degree. Importantly, cases having
on education level have been removed from the data as well.
Example 2 - Selection for 2 Variables
The syntax below selects cases based on gender and education level: we'll keep only female respondents having at least a Bachelor's degree in our data.
crosstabs educ by gender.
*Select females having a Bachelor's degree or higher.
select if(gender = 0 & educ >= 4).
*Reinspect contingency table.
crosstabs educ by gender.
Result
Example 3 - Selection for (Non) Missing Values
Selections based on (non) missing values are straightforward if you master SPSS Missing Values Functions. For example, the syntax below shows 2 options for deleting cases having fewer than 7 valid values on the last 10 variables (overall to q9).
select if(nvalid(overall to q9) >= 7)./*At least 7 valid values or at most 3 missings.
execute.
*Alternative way, exact same result.
select if(nmiss(overall to q9) < 4)./*Fewer than 4 missings or more than 6 valid values.
execute.
Tip 1 - Inspect Selection Before Deletion
Before deleting cases, I sometimes want to have a quick look at them. A good way for doing so is creating a FILTER variable. The syntax below shows the right way for doing so.
compute filt_1 = 0.
*Set filter variable to 1 for cases we want to keep in data.
if(nvalid(overall to q9) >= 7) filt_1 = 1.
*Move unselected cases to bottom of dataset.
sort cases by filt_1 (d).
*Scroll to bottom of dataset now. Note that cases 459 - 464 will be deleted because they have 0 on filt_1.
*If selection as desired, delete other cases.
select if(filt_1).
execute.
Quick note: select if(filt_1). is a shorthand for select if(filt_1 <> 0). and deletes cases having either a zero or a missing value on filt_1.
Result
Cases that will be deleted are at the bottom of our data. We also readily see we'll have 458 cases left after doing so.
Tip 2 - Use TEMPORARY
A final tip I want to mention is combining SELECT IF with TEMPORARY. By doing so, SELECT IF only applies to the first procedure that follows it. For a quick example, compare the results of the first and second FREQUENCIES commands below.
temporary.
*Select only female cases.
select if(gender = 0).
*Any procedure now uses only female cases. This also reverses case selection.
frequencies gender educ.
*Rerunning frequencies now uses all cases in data again.
frequencies gender educ.
Final Notes
First off, parentheses around conditions in syntax are not required. Therefore, select if(gender = 0). can also be written as select if gender = 0. I used to think that shorter syntax is always better but I changed my mind over the years. Readability and clear structure are important too. I therefore use (and recommend) parentheses around conditions. This also goes for IF and DO IF.
Right, I guess that should do. Did I miss anything? Please let me know by throwing a comment below.
Thanks for reading!
THIS TUTORIAL HAS 29 COMMENTS:
By Vincent on May 13th, 2016
I noticed that in my syntax the code only works if there are no spations in between, like:
SELECT IF End=1.
By Ruben Geert van den Berg on May 13th, 2016
Hi Vincent!
What happens if you do throw in a bunch of spaces? It shouldn't make any difference as in:
data list free/id.begin data
1 2 3 4 5
end data.
select if id = 1.execute.
By Md. Uzzal Chowdhury on August 2nd, 2016
good
By Martin on September 17th, 2016
Hello Ruben,
I am a Statistics graduate. I think all your SPSS tutorials are very good, I like them a lot. Thank you !
Sincerely
Martin
By Md. Uzzal Chowdhury on November 12th, 2016
need to know more SPSS