How would you respond to the following argument? This talk of sampling distributions is...

How would you respond to the following argument? This talk of sampling distributions is ridiculous! Consider Example A of Section 8.4. The experimenter found the mean number of fibers to be 24.9. How can this be a “random variable” with an associated “probability distribution” when it’s just a number? The author of this book is guilty of deliberate mystification!

Reference

Poisson Distribution

The first moment for the Poisson distribution is the parameter λ = E(X). The first sample moment is