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JamesNieh
Level I

Risk Ratios and meaning the ChiSquare p-values

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?

 

 

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Accepted Solutions
txnelson
Super User

Re: Risk Ratios and meaning the ChiSquare p-values

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.

Jim

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4 REPLIES 4
txnelson
Super User

Re: Risk Ratios and meaning the ChiSquare p-values

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.

Jim
JamesNieh
Level I

Re: Risk Ratios and meaning the ChiSquare p-values

Thank you!

JamesNieh
Level I

Re: Risk Ratios and meaning the ChiSquare p-values

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?

 

 

txnelson
Super User

Re: Risk Ratios and meaning the ChiSquare p-values

Your interpretation is correct.

Jim