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/