hi,

I'm looking for a statistical test to prove (statistically) that the cumulative curve is S-shape

When I try to look for answer I get 2 types of answers:
1. test to prove that the data is from normal distribution. it is true that the cumulative curve of a normal distribution is S-shaped but it does not mean that every S-shape curve is from a normal distribution, this means that this test does not supply what i am looking for


2. ways to fit a S-shape curve to a data on a graph. This just gives an S-shape line that is close to the data but does not provide a statistical test to statistically significant prove that the data is from an S-shape form.

Thank you,
Mor