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# When to reject null hypothesis? watch

1. Help!

So when the observed value is higher than the critical value we reject the null hypothesis right?

When do we accept it?
Help!

So when the observed value is higher than the critical value we reject the null hypothesis right?

When do we accept it?
If you're testing if something is increasing, then yeah you reject if the observed value if it's larger than the critical value. If the observed value was less than the critical value, we do not reject the null hypothesis.
3. You and I might be doing it totally different ways.

But, if the observed value is higher than the critical value, we do NOT reject it, if it is lower we have strong evidence to reject it, if it is much lower we have very strong evidence to reject it.

That's based on the probability calculated given an event that lies within the bounds of the alternative hypothesis, when you apply the null hypothesis.

For instance, if:
h0 says the mean is 4.
h1 says the mean is not 4.

That's a two tailed test (usually we are looking for 95% certainty, so the critical value is 0.025)

So, if we plug in what we observe into h0 and get 0.09 then we have no evidence to reject it.

That's how I understand it currently, anyway, I haven't really started revising S2 yet.
4. for chi squared and spearmans rho: calculated value must be greater than the critical for it to be significant (rejects null hypothesis)
for the mann whitney U: calculated must be below the critical value for it to be significant (reject null hypothesis)
Help!

So when the observed value is higher than the critical value we reject the null hypothesis right?

When do we accept it?
It depends on what inferential test you use some may be higher some may be lower than the critical value. When you find your results to be be significant you reject the null hypothesis and opposite for not significant.
6. (Original post by NutE)
for chi squared and spearmans rho: calculated value must be greater than the critical for it to be significant (rejects null hypothesis)
for the mann whitney U: calculated must be below the critical value for it to be significant (reject null hypothesis)
Is calculated another way of saying observed value???
Is calculated another way of saying observed value???
If you're not calculating the value but you're given the value, then yes they're the same.

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