I am currently studying Logistic Regression. I am facing a problem with understand the sentence in the red circle below. I am trying to figure out what he/she means by the sentence. Please let me have your opinion on this. I am sorry if I have placed my question in the wrong places. Thank you.
Working with grouped data allows you to utilize some measures of fit that cannot be used in the individual data approach. For example, let us consider the deviance. Using grouped data, as the number of groups increases, the distribution of the deviance converges to a chi-square distribution with $n-p$ degrees of freedom, where $n$ is the number of groups and $p$ is the number of model parameters. Thus, in large populations with relatively high number of groups, the deviance provides a measure of model fitting. This is not the case for models built using the individual one/zero data, because in this case the deviance does not converge to particular types of known distributions. Similar considerations can be made for other statistics potentially appliable to the assessment of model fitting in logistic regression (e.g., the Pearson chi-square).