Sargan test P value = 0 meaning

[Salman Ikram]

Hi

What does a sargan test p value = 0 imply? does it mean my instruments are valid? I read that sargan test p values between 0.1 and 0.25 mean that instruments are not valid, however I am confused what does a pvalue of 0 mean?

Estimation would be using 2sls:

Ivreg2 Y X Controls (X = Z1 Z2)

[Sebastian Kripfganz]

The null hypothesis of the Sargan test is that all overidentifying restrictions are valid. A very small p-value indicates rejection of this null hypothesis, which is likely caused by instrument invalidity.