is $z$ observable what is censored regression what is the difference between the censored and random regression problem? what is random censored regression why is it difficult to find the best solution to an observable regression problem? which random variable is observable which variables are observable what is the problem with censored regression what is the problem with random censored regression what is the problem of censored regression what is random censored regression? which variable is considered observable which of the following is observable? how to calculate the distribution of x$ which is an observable variable in a random sample? what is the random censored regression problem? what is the problem of censored regression what is the random censored regression problem how to find the distribution of $z$? what is a random censored regression