Yue Yin posted on Tuesday, April 03, 2018 - 1:43 pm
Hi, Dr. Muthén,
We ran an IRT analysis with the binary variables. After we ran it, the output illustrated the issues: WARNING: THE BIVARIATE TABLE OF ELNFR015 AND ELNFR009 HAS AN EMPTY CELL.
Below are the partial information about the covariance convergence: Number of observations 3246
Number of dependent variables 52
the covariance convergence for the four items are .356, .195, .391, .554.
And all of the covariance convergence are low, and we had to change the minimum covariance convergence to .06 because we do not have that many. And below are the percentage for the four items(like the item difficulty): ELNFR015 Category 1 0.150 183.794 Category 2 0.850 1040.437 ELNFR009 Category 1 0.386 704.410 Category 2 0.614 1121.340 ELNFR115 Category 1 0.103 138.481 Category 2 0.897 1200.990 ELNFR102 Category 1 0.439 781.341 Category 2 0.561 999.914
I checked several discussions published before, that the empty cell is due to the correlation of the two variables of 1. But here I am wondering what kind of reason might result in this? Is because the low convergence, and percentage of the item(difficulty)are too high or too low?
When you say "covariance convergence" perhaps you mean "covariance coverage". If that's the case, coverage of only .356, .195, .391, .554 is too low and missing data handling would rely too much on distributional assumptions. The empty cell message may be due to the high degree of missing.
Yue Yin posted on Tuesday, April 03, 2018 - 2:50 pm
But the problem is that the covariance converage for other variables are also low just like the four values I listed before, how come other variables do not appear the empty cell message? Is it due to the percentage?