When we are performing maximum likelihood estimation (MLE) to estimate parameters, the fit function is often to -2 * LL, rather than just LL. I also see this "-2LL" term expressed as "deviance". Why do we multiply log likelihood times -2? Is it if we are trying to minimize the function rather than maximize? What is the purpose of it being multiplied by (a) a negative number, and (b) a "2"?
Some locations where "-2 log likelihood" is expressed are below:
- https://www.restore.ac.uk/srme/www/fac/soc/wie/research-new/srme/modules/mod4/6/index.html
- https://stats.idre.ucla.edu/stata/output/logistic-regression-analysis/
- https://stats.idre.ucla.edu/spss/output/logistic-regression/
- https://medium.com/@analyttica/log-likelihood-analyttica-function-series-cb059e0d379
- https://www.researchgate.net/post/SPSSWhat-should-I-do-when-my-2-log-likelihood-is-really-high-r-squared-value-really-low-and-a-0000-result-for-the-Hosmer-Lemeshow-goodness-of-fit
- https://www.ibm.com/docs/en/spss-statistics/27.0.0?topic=model-likelihood-ratio-tests
- https://www.ibm.com/support/pages/there-general-rule-what-good-value-2-log-likelihood-logistic-regression-model