Question

I'm reading a research article and am having trouble understanding the following..
"Regardless of whether the book was written by a new or established author, being positively reviewed significantly increased sales; a positive review generated between a 32% and 52% increase in demand (no significant difference between coefficients, z = 1.0, p > 0.30)."
What does the z here refer to?

Answer 1

z is the standard z-score

Answer 2

the way z is often computed is this

\[\Large z = \frac{x-\mu}{\sigma}\]

Answer 3

mu is the mean, sigma is the standard deviation