Technically you can make the tolerance for age any number. But then you have to consider that the standard deviation for age will be +/- seven years. This might be an [huge] issue for instance if you will be conducting any age specific analysis.

Thanks for the feedback

Thank you for your reaction! First I got an error, but when I used the values 0 and 1, it worked!

Hi Areg, sure! I'll be filming the video in the next week or so.

@@lizzylartey Thank you! If you can please explain how to do the 1:2 matching and make it be exactly a 1:2 ratio, that would be awesome. Right now, I get 80 matches to 192 matches for explains so its not 1:2. Thanks!

Hi Jennifer, it likely means the differences in sample a and sample b are not by chance (i.e. the groups are difference based on those variables). Also chi-sqaured test are used for categorical variables (e.g. yes, no), if you are trying to find the significance of the contunuous variable try using a t-test. If you separate out the groups and run descriptives on it, do you notice any differences ( i.e. lets say you have a variable age, in group a the mean age is 30, vs group b the mean age is 25)?

Glad it was helpful!

No worries glad it was helpful

Sorry for the late reply. To the best of my knowledge, propensity score matching ( PSM) is a way in which a case and control can be matched. Both ways ( the way I showed in the video and PSM) can be used to minimize the selection bias in a case-control study. However, propensity score matching matches based on the propensity score ("conditional probability of receiving the treatment rather than the control given the observed covariates" (Rosenbaum and Rubin 1983)). The method calculates the score for each subject and then matches subjects with similar or the same scores.The way I showed in the video doesn't match based on any score, I would liken it to a filtering technique almost. It basically says find me everybody with these covariates but belongs to treatment or no treatment group. Below are some open source links to propensity score matching that you may find helpful. www.ncbi.nlm.nih.gov/pmc/articles/PMC3144483/ www.publichealth.columbia.edu/research/population-health-methods/propensity-score-analysis www.frontiersin.org/articles/10.3389/fphar.2019.00973/full

@@lizzylartey i would love a tutorial on how to use the PSM tool here in SPSS. Do you have a video about it? Or do you know of someone with a video about it? Thanks

A suggestion was made by @Ariel Hasidim in the comments. In the dialogue box "Names for Match ID variables" type in whatever you want the variable to be called, followed by a space and then another name for the match ID variables. This works as long as there are other available matches that match your criteria, so consider the match tolerance levels.

@@lizzylartey thank you for the video I'm wondering if I do 1:2 ratio and use the technique that you mentioned, I would have to increase the tolerance on the matching variables right? I didn't quite understand how to do that? So if I want year of birth to have a tolerance of 5 years then I would right the tolerance as "5" or "0.5"?

@@melissa-re6oi Hi Melissa, It would be 5

Just add more "Names for Match ID Variables" names with space between in the dialog (fourth input field)

Thanks for watching and thanks for your question. Typically when there are dots in the two columns ( i.e. match group variable and match ID variables) it may mean that there are no matches based on the variables and the match tolerances selected. Additionally, if you have written the syntax for this you may want to double-check the code. Warning messages may show up as the example below. If it does review the line below the warning. It may provide you with some ideas about where the error is coming from. E.g. >Warning # >Invalid Number

@@lizzylartey Hello, thanks for the response. Just from visualization, I see there are enough cases to be matched on. Also, when I get Warning 5.3, there's no other explanation of why the error is happening...

@@jaemoolee4665 Hi, did you manage to solve this issue? I have the same problem and cannot find a solution.

It may depend on the version of SPSS. Try some of the solutions in the following IBM support thread: community.ibm.com/community/user/datascience/communities/community-home/digestviewer/viewthread?MessageKey=fb29e2f2-fafc-4f5a-8223-acb37c1d1b54&CommunityKey=886b6874-0fb1-402c-8243-c70ef8179a99&tab=digestviewer#bmfb29e2f2-fafc-4f5a-8223-acb37c1d1b54

Dear Jae, I am just reading your message now and probably you already fixed it as it is a year ago, but maybe this helps: Did you already try to label the case control 0 and 1? I first labeled it with 1 and 2, but then I had the same problem as you. But when I used 0 and 1 for some magical reason it worked! Hope it will work out. Best wishes, Manon

I'm glad it helped!

That's awesome

Thank you.Glad it was helpful!