what is a random variable which is an invariant random variable? what is the probability density of a random variable random variable that is invariant under null and alternative hypotheses what is the random variable $x$ under null what is the density of the random variable x what is the probability of predicting one random variable under a null hypothesis? what is the probability density of a random variable which random variable is non-null and is not invariant? which variable is invariant under null which random variable has an invariant probability what are random variables that are invariant what is a random variable with a null hypothesis what is the probability density function of random variable random variable that is invariant under null and alternative hypotheses which random variable is invariant under null and alternative hypotheses? what is the probability density function of the variable x$ what is the random variable that is invariant under null hypothesis which random variable is an invariant variable under null hypothesis? which random variable is invariant