What is the "direct likelihood" point of view in statistics?

Question

I am reading a Springer title from 1997 called Applied Generalized Linear Models by James K. Lindsey. In the preface, Lindsey writes

For this text, the reader is assumed to have knowledge of basic statistical principles, whether from a Bayesian, frequentist, or direct likelihood point of view[.]

I've heard of the Bayesian and frequentist/Fisherian points of view - what is the "direct likelihood" point of view? I've been searching on that term to no avail - pretty much just getting that exact excerpt in my DDG search results. Does it go by a different name now, or has it been obsoleted?

Answer 1

Hugo, I have seen the term "Direct-Likelihood" used as a method with respect to handling missing data (aka missingness, e.g. clinical trial) via using likelihood-based mixed-effects models, modeling the missing data as random.

There is a very good Tutorial paper on this:

Direct likelihood analysis versus simple forms of imputation for missing data in randomized clinical trials Clinical Trials 2005 2: 379 Caroline Beunckens, Geert Molenberghs and Michael G Kenward https://www.researchgate.net/publication/7452657_Direct_likelihood_analysis_versus_simple_forms_of_imputation_for_missing_data_in_randomized_clinical_trials

They also mention that the direct-likelihood method is also termed: likelihood-based MAR analysis, likelihood-based ignorable analysis, random-effects models, random-coefficient models.