# Hypothesis tests

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#1
The number of white corpuscles on a slide has poisson distribution with mean 3.5. After certain treatment another sample was taken and the number of white corpuscles found to be 8. Test at the 5% level whether the mean has increased.
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15 years ago
#2
Arghhh....I hate hypothesis testing.

Basically it involves looking at the resuts from a sample (i.e. number of corpuscles =8) and deciding how likely it is that those results (or worse results i.e. >8) could have occurred under the null hypothesis (i.e. mean = 3.5). If the probability of the sample results occurring under the null hypothesis is deemed too low (i.e. under 5%), the null hypothesis is rejected and the alternative hypothesis is accepted.

So, null hypothesis: λ = 3.5
alternative hypothesis: λ > 3.5

If null hyp. is true:
Then X~Po(3.5)

So, P(X>=8) = 0.0099

Since 0.0099<0.05, this is treated as significant and the nulll hypothesis is rejected. Therefore, there is sufficient evidence to suggest that the mean has increased.

Sorry if i haven't explained this very well.
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#3
no thats great thanx a lot
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