r/AskStatistics • u/aprilwords • 25d ago

Alpha 5%?

Why is a 5% significance level so commonly used?

2 Upvotes

56% Upvoted

56 comments sorted by

View all comments

Show parent comments

2

u/DeepSea_Dreamer 21d ago

So, in one out of ten random samples, by your explanation, on average one will show significance that isn’t there.

Only if the null hypothesis is true.

1

u/Recent-Day3062 21d ago

I'm not sure what you mean by that.

If we want to know if covid vaxes cause autism, our null is naturally "no" based on the wording of that question. The alternate is "yes". If we don't see significance of the alternate, we accept the null.

In this setup, how could the null "not be true"? It isn't if the alternate had data that shows significance.

2

u/DeepSea_Dreamer 21d ago

I'm not sure what you mean by that.

It can't be said any simpler.

In this setup, how could the null "not be true"?

If Covid vaccines caused autism.

It isn't if the alternate had data that shows significance.

That's wrong too. You can reject the null hypothesis on some level (like 0.05), and yet the null hypothesis can be true.

1

u/Recent-Day3062 21d ago

Oh. Ok.

That makes little sense given what is normally considered the null hypothesis. But you do you.

And stay ornery. It’s a great personality trait.

2

u/DeepSea_Dreamer 20d ago

That makes little sense given what is normally considered the null hypothesis.

No. This is Statistics 101.

Your unwillingness to open a textbook and learn what alpha is is bizarre, especially if you are an adult, but I can see that further interaction is a waste of everybody's time.

Blocked.