I tested two models and one is nested inside another. Nested model has 2 parameters and the bigger model has 4. I got the ln likelihood of each models. I know how to calculate the P value using twice the difference of ln likelihoods, since twice the difference of ln likelihoods is following chi square distribution with degree of freedom equal to the difference in the number of parameters between the two models.

How can I calculate z-value from chi-squre distribution with 2 df? I need z-values for further meta-analysis using METAL https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2922887/


closed as unclear what you're asking by mdewey, Michael Chernick, Jeremy Miles, Frans Rodenburg, Peter Flom Jun 14 at 11:54

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    $\begingroup$ You can use software, look it up in tables, or recognize that the chi-squared distribution with 2 df is an exponential distribution and easily calculate p-values yourself. What kind of answer are you looking for? $\endgroup$ – whuber Jun 10 at 18:16
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    $\begingroup$ What quantity is it you want a z-value of, exactly? $\endgroup$ – Glen_b Jun 11 at 3:22
  • $\begingroup$ If I understand it correctly METAL uses p-values not z although presumably it can transform z into p. Can you clarify by editing your question preferably with a small example just what steps you can do and where you cannot. $\endgroup$ – mdewey Jun 11 at 7:55