Thank you for your advice. I appreciate your kindness. Very sorry to bother you while you are busy. I remembered making a backup of all R-packages before late April 2021. Therefore, I loaded (downgraded) all packages and ran the program. ===== Meanwhile, I have been in trouble of which the values in the output are slightly different between late April 2021 and August 2021. The source code, R environment, and csv files are the same (R-3.6.1 in Windows 10). ===== For a different dataset made up before late April 2021, I could reproduce the results. So, the reason that I could not reproduce the results using the dataset, which I posted you, seems that some problems have occurred in the period, which I did not make a back up, such as OS update or consistency with other packages. I don't want to cause you any more trouble, so I'll do some more research on my own for solving. Thank you very much. Best regards 2021?8?27?(?) 10:48 Ben Bolker <bbolker at gmail.com>:
These are basically harmless. lmerTest substitutes its own version of `lmer`. This is often confusing, but when it works it provides a seamless user experience (i.e., people load lmerTest and everything works the same but they also get denominator degrees of freedom and p-values in their summary tables). It also defines its own version of 'step'. You can see the help for `lmerTest::lmer` or `lmerTest::step` for an explanation of why these functions are masked. -- Dr. Benjamin Bolker Professor, Mathematics & Statistics and Biology, McMaster University Director, School of Computational Science and Engineering Graduate chair, Mathematics & Statistics