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# hypothesis testing question! watch

1. A drugs company produced a new drug for asthma sufferers and claimed an 85% success rate. A doctor thought that the success rate was lower than this but decided to test it on 18 of her patients.
After 9 months, 13 said their asthma symptoms had improved.
Carry out a hypothesis test at 5% significance level to examine whether the drug appears to have improved their symptoms.

so for the null hypothesis i have stated that
p=0.85 ( the probability of the new drug success)
alternative: p> 0.85 ( the probability of the new drug success increase)
now actually I'm not sure if i have stated the alternative hypothesis right!!!
I'm thinking it might be p<0.85! (this confuses me a bit (A doctor thought that the success rate was lower than this?!!))

but i solved it both ways!
and for both i accepted the null hypothesis!
but i was wondering if someone can explain to me what their choice of the alternative hypothesis would be?

thanks!
2. (Original post by deema21)
A drugs company produced a new drug for asthma sufferers and claimed an 85% success rate. A doctor thought that the success rate was lower than this but decided to test it on 18 of her patients.
After 9 months, 13 said their asthma symptoms had improved.
Carry out a hypothesis test at 5% significance level to examine whether the drug appears to have improved their symptoms.

so for the null hypothesis i have stated that
p=0.85 ( the probability of the new drug success)
alternative: p> 0.85 ( the probability of the new drug success increase)
now actually I'm not sure if i have stated the alternative hypothesis right!!!
I'm thinking it might be p<0.85! (this confuses me a bit (A doctor thought that the success rate was lower than this?!!))

but i solved it both ways!
and for both i accepted the null hypothesis!
but i was wondering if someone can explain to me what their choice of the alternative hypothesis would be?

thanks!
The null hypothesis is that the claim p=0.85 is correct, and the alternative hypothesis (the doctor's hypothesis) is that actually the drug works less well than this, so the alternative hypothesis should be p<0.85.
3. (Original post by Mark13)
The null hypothesis is that the claim p=0.85 is correct, and the alternative hypothesis (the doctor's hypothesis) is that actually the drug works less well than this, so the alternative hypothesis should be p<0.85.
But then the question says carry out a test to examine whether the drug appears to have "improved" their symptoms?
Now, i'm thinking is that a 2 tailed test?
is it possible?
4. If someone's symptoms have been improved, it is assumed that the drug has succeeded as the drug has managed to remove the symptoms.

Also i'll quote these words "examine whether": meaning use the hypothesis test to see if has or has not improved.

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5. (Original post by deema21)
But then the question says carry out a test to examine whether the drug appears to have "improved" their symptoms?
Now, i'm thinking is that a 2 tailed test?
is it possible?
I'm pretty sure it's just a poorly-worded question: if they wanted you to test whether the drug had improved the patients symptoms, you'd need a control success rate to compare the 85% figure with. As it stands, I think they just mean do a test on the null hypothesis "the drug has an 85% success rate", and the alternative hypothesis "the drug has a less than 85% success rate".
6. I think that they mean that the alternative hypothesis is p>0.85, because the part of the question telling you what you should actually do says about improved symptoms. The first part of the question is basically explaining why the doctor carried out the hypothesis test, but the question's asking you about whether it's improved the symptoms, therefore you go with an increased success rate. I think however they might accept a two-tailed test as well as the one-tailed test, all my stats papers allowed both
7. (Original post by Zaphod77)
I think that they mean that the alternative hypothesis is p>0.85, because the part of the question telling you what you should actually do says about improved symptoms. The first part of the question is basically explaining why the doctor carried out the hypothesis test, but the question's asking you about whether it's improved the symptoms, therefore you go with an increased success rate. I think however they might accept a two-tailed test as well as the one-tailed test, all my stats papers allowed both
No that is incorrect.

The question says the doctor decided to do a hypothesis test to see if the rate of success was lower than 85% therefore the alternate hypothesis is p<0.85.

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8. (Original post by Joshmeid)
No that is incorrect.

The question says the doctor decided to do a hypothesis test to see if the rate of success was lower than 85% therefore the alternate hypothesis is p<0.85.

Posted from TSR Mobile
It does say that, but that's saying why he decided to do a hypothesis test. It then says "Carry out a hypothesis test to see if the symptoms have improved", indicating that you shouldn't test what the doctor thought but the opposite. I took the bit I just quoted as the main part of the question as that is commanding what to do, if you get what I mean.
9. (Original post by Zaphod77)
It does say that, but that's saying why he decided to do a hypothesis test. It then says "Carry out a hypothesis test to see if the symptoms have improved", indicating that you shouldn't test what the doctor thought but the opposite. I took the bit I just quoted as the main part of the question as that is commanding what to do, if you get what I mean.
I understand, pretty poorly worded question IMO.

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10. This is an incredibly badly worded question. What's missing here is the clarification that "success" = "improved symptoms".

It's the symptoms that improve, not the success rate, so we are testing the doctor's hypothesis that we have a success rate lower than the stated one, not a higher rate (which would be an "improvement in the success rate").

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Updated: March 27, 2013
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