nav[aria-label="Primary Navigation"] { padding: 0; & ul { list-style: none; width: 100%; display: flex; flex-direction: row; justify-content: start; align-items: start; gap: 30px; padding: 0; & li { margin: 0; } & ul li { list-style: none; } } }

Risk Ratios and meaning the ChiSquare p-values

JamesNieh

Hi, I'm trying to understand the meaning of the ChiSquare p-values calculated for Risk Ratios as part of the Proportional Hazards Fit platform. In the attached image, I have run an analysis of the effect of heat shock durations (in hours) and bee origin (feral or managed colonies) on bee survival. The Risk Ratio lead me to this interpretation: the risk of death for bees exposed to 0 h vs. 0.5 h of heat shock is 1.472. But what does P<0.0001 mean?

I am guessing that the what the Risk Ratio p-value is saying is that "the probability of this ratio being equal to 1 is <0.0001"

Is this a correct interpretation?

Screen Shot 2021-07-25 at 10.04.10 AM.png

Accepted answers

txnelson

The way to interpret the p value for a Chi Square, is, what is the probability of the relationship measured is by random chance. Therefore, the finding is highly significant that the data did not happen by chance......something is going on with the Heat shock duration

If you select the Help Tool (?) and click on the Effect Likelihood Ratio Tests table you will get the following definition

Effect Likelihood Ratio Tests

Shows the likelihood ratio chi-square test of the null hypothesis that the parameter estimates for the effects of the covariates is zero.

All comments

txnelson

If you select the Help Tool (?) and click on the Effect Likelihood Ratio Tests table you will get the following definition

Effect Likelihood Ratio Tests

Shows the likelihood ratio chi-square test of the null hypothesis that the parameter estimates for the effects of the covariates is zero.

JamesNieh

Thank you!

JamesNieh

Actually, on closer look, what I wanted to know is the not the meaning of the L-R Chi Square, but rather the P-values given for the Risk Ratios. I understand your interpretation of their being an overall effect of heat shock duration. My question is avout the interpretation of P>Chisq for Level1risk =0 and Level2risk=0.5.

I am guessing that the what the Risk Ratio p-value is saying is that "the probability of this ratio being equal to 1 is <0.0001"

Is this a correct interpretation?

Screen Shot 2021-07-28 at 11.39.21 AM.png

txnelson

Your interpretation is correct.