Monthly rainfall at a site is classified in two groups one g

Monthly rainfall at a site is classified in two groups: one group for El Niño months and the other for
La Niña months (defined according to sea surface temperature in the Pacific Ocean). We have 100
months for each group. The variance of each group is the same. Is it true that rainfall during El Niño
is different to that during La Niña? What type of test would you run? What is H0? Suppose you get
a p-value = 0.045. What is the conclusion of the study?

Solution

We cant not so sure until we have the mean but we can do a test of variance

If the variance of each group are the same so maybe they will have the same rainfall for both group

Type test: As n=100 we can use Z test or T test

Ho: Monthly rainfall el niño = monthly rainfall la niña

Suppose you get
a p-value = 0.045. What is the conclusion of the study?

With alpha = 0.05

we can say that it is true that rainfall during El Niño
is different to that during La Niña because p-value < critical value (alpha)