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# S2 Type 2 error

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1. Can someone explain 8iv.

I have forgotten what a type 2 error is.

so far I've put x-po(4.8)

Cheers.

https://c08863e2f4be4cccd221320d0030...20S2%20OCR.pdf
2. (Original post by Super199)
Can someone explain 8iv.

I have forgotten what a type 2 error is.
We have Google for that.

Basically, type2 is H0 false, but we don't reject it.

so far I've put x-po(4.8)

Cheers.
In part iii you worked out the values for which we reject H0, and so, you can work out the values for which we accept H0.

But the actual distribution is Po(4.8). So, what's the probability of getting those latter values given this distribution.
3. (Original post by ghostwalker)
We have Google for that.

Basically, type2 is H0 false, but we don't reject it.

In part iii you worked out the values for which we reject H0, and so, you can work out the values for which we accept H0.

But the actual distribution is Po(4.8). So, what's the probability of getting those latter values given this distribution.
Isn't there something to do with the mean as well?

Ho = lamda = 0.75 how do you show that this is false?
I can work out the values for which we accept Ho.

But I don't get how that relates to Ho being false
4. (Original post by Super199)
Isn't there something to do with the mean as well?

Ho = lamda = 0.75 how do you show that this is false?
You don't show it's false. You know it's false since you're told the value of lambda is actually something else.

I can work out the values for which we accept Ho.
And you need the probablities of those values arising with the Po(4.8) distribution.

But I don't get how that relates to Ho being false
You're told it's false.
5. (Original post by ghostwalker)
You don't show it's false. You know it's false since you're told the value of lambda is actually something else.

And you need the probablities of those values arising with the Po(4.8) distribution.

You're told it's false.
Ok so a type 2 error is when Ho is false, which you are told it is already.

You are looking for the probability that this occurs? So why are we looking for a probability for which we accept Ho?
When it should be rejection values as surely that makes Ho false?
6. (Original post by Super199)
Ok so a type 2 error is when Ho is false, which you are told it is already.

You are looking for the probability that this occurs? So why are we looking for a probability for which we accept Ho?
When it should be rejection values as surely that makes Ho false?
A type 2 error is when H0 is false AND/BUT you accept it as true, i.e. you don't reject it.
7. (Original post by ghostwalker)
A type 2 error is when H0 is false AND/BUT you accept it as true, i.e. you don't reject it.
Got it cheers.
Do you mind helping with 5i

P(y<0) -> p(z< (0-mu)/ (mu/2)) =0.5

Idk im slightly confused the ms has 0-mu / mu/2 = 2
Where does 2 come from?
Attached Images

8. (Original post by Super199)
Got it cheers.
Do you mind helping with 5i

P(y<0) -> p(z< (0-mu)/ (mu/2)) =0.5

Idk im slightly confused the ms has 0-mu / mu/2 = 2
Where does 2 come from?
Should be -2, rather than 2.

But, I'd like to see the markscheme.
9. (Original post by ghostwalker)
Should be -2, rather than 2.

But, I'd like to see the markscheme.
My bad it does say -2.
But yeah, why is it?
Attached Images

10. (Original post by Super199)
My bad it does say -2.
But yeah, why is it?
Just the algebra:

11. (Original post by ghostwalker)
Just the algebra:

oh I see. Thanks
12. (Original post by ghostwalker)
Just the algebra:

Sorry to bother you again, but do you mind helping me with 7i

With normal it is X-mu/sigma

But how come it is 80-c/sigma

In this case. Isn't mu=80?
13. (Original post by Super199)
Sorry to bother you again, but do you mind helping me with
Two questions is enough for now. I'll leave it for someone else.
14. (Original post by ghostwalker)
Two questions is enough for now. I'll leave it for someone else.
It's cool I've sorted this now

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