Benchmark for PctCert in Latent Class CBC

Question

Hey,

in my Latent Class Analysis I get values of  around 30 for the PctCert for several group solutions. This seems rather low to me. Does anyone have a benchmark recommendation for me or an idea what could potentially cause this?

Thanks in advance

Answer 1

The Latent Class technical paper (https://www.sawtoothsoftware.com/download/techpap/lctech.pdf) has a section on page 9 (A Numeric Example) where  known utilities are used to see how well they are recovered and provides some examples of Percent Certainty and the other fit statistics.  I don't do a lot of LC work, though, and don't feel like I have a good grasp of recommendations on real data sets.  Perhaps someone else will be able to chime in with those.

Answer 2

Percent Certainty is also called Pseudo R-squared.  This fit statistic is dramatically affected by the number of classes you request.  If you request just two classes, the % Certainty will be relatively low.  If you request more classes, especially beyond 10 (for argument sake), the fit will be relatively high.

If you haven't already done so, I recommend using HB to assist you in cleaning the data of random responders, speeders, etc. prior to running latent class.

Comments

Hi Brian, thanks for your answer. I would like to have 3-5 classes, but the PctCert stays more or less the same at around 30 %. Could you please elaborate a bit more on how to use HB for data cleaning? Which criteria should I use to detect bad answers which cannot be used for LC?
Cheers

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Sure, please look at the short article I wrote on the subject at: https://www.linkedin.com/pulse/identifying-consistency-cutoffs-identify-bad-respondents-orme/

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Hi Brian,
thanks for your answer. Despite doing what you proposed, the PctCert still is around 0.3. Could you please tell whether you think this is as issue?
From what I know values for Pseudo R-squared between 0,.3 and 0.4 are considered as good.
Thanks in advance

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Without having other data sets to compare to, it's hard to know if PctCert of 0.3 is bad or good.

So, I just looked at 6 CBC datasets that were collected back in the mid-1990s that we use for comparison.  Here are the PctCert scores for Latent Class MNL, 4-group solutions:

Tropt - 0.30
Study1 - 0.33
Study2 - 0.37
Study3 - 0.35
Phone - 0.37
Diaper - 0.28

So, a sampling of 6 professional CBC data sets from the 1990s (when respondents probably were more conscientious than they are today) shows a range of PctCert of 0.28 to 0.37.  I have about 25 such datasets, and I just randomly picked 6 of them.

Your study falls within that range.  So, from my perspective there isn't evidence that you should think your fit is any worse than other reasonable CBC datasets.