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visits member for 1 year, 10 months
seen Sep 13 '13 at 23:49

Oct
6
comment Is it possible to do this Poisson problem in Binomial?
i got it! going back to question (a) i tried to find the prob $(\frac{364}{365})^{80000}$ why is that wrong?
Oct
6
comment Is it possible to do this Poisson problem in Binomial?
Hi Henry, question (b) asks (b) both partners celebrated their birthday on the same day of the year. the solution says The probability that an arbitrary couple were born on the same day of the year is $\frac{1}{365}$. why is that? why isn't it the same $\frac{1}{365^2}$
Oct
5
comment Performing hypothesis test for the difference of population means: paired comparisons
@MichaelChernick to summarize, I cannot use the 2 sample independent t test because there's a strong correlation (or dependence) between the two variables. The experimental design is better suited with paried comparisons. correct?
Oct
4
comment Why does negative binomial random variable uses ${n-1 \choose r-1}$ instead of ${n \choose r}$ as coefficient?
This is a good answer, Thank you! however what I don't understand is that with ${n-1 \choose r-1}$ aren't we skipping the last trial? It's a guaranteed success, but we shouldn't ignore it
Oct
4
comment Why does negative binomial random variable uses ${n-1 \choose r-1}$ instead of ${n \choose r}$ as coefficient?
i understand r-1 success in n-1 trial part, but the last trial must be a success then that makes it ${n \choose r}$... if we do ${n-1 \choose r-1}$ we lose the last trial!
Oct
4
comment Performing hypothesis test for the difference of population means: paired comparisons
@MichaelChernick why do you think using the formula for 2 sample t test is incorrect in this scenario? I think we can use it because has been used to determine difference of population means. my thoughts are, if anything, this and the paired t test should come to the same conclusion...
Oct
4
comment Performing hypothesis test for the difference of population means: paired comparisons
@MichaelChernick yes, thank you for answering, but it looks like you have discussed the topic in CV, but Im wondering what is CV...
Oct
4
comment Performing hypothesis test for the difference of population means: paired comparisons
Yes! an answer!!! Michael you're AWSOME!!!!
Oct
4
comment Performing hypothesis test for the difference of population means: paired comparisons
thanks for answering michael, what exactly is a CV?
Sep
30
comment How do we identify a probability problem as a conditional probability problem?
@DilipSarwate minor math latex error
Sep
30
comment How do we identify a probability problem as a conditional probability problem?
@DilipSarwate if they had used the keyword "Given" it would've been much easier, but here it doesn't use the keyword "Given". What other clues should i look for?
Sep
24
comment Solving an equation with three quadratic radicals in the set of real numbers
2 seems to work...
Sep
24
comment Probability in flipping a coin
@did the answer is accepted, when i unaccepted the answer, I added questions in the comment beneath the answer, and Jean provided answers to my questions, so i reaccepted his answer.
Sep
23
comment Confusion on the meaning of confidence interval
it seems quite reasonable that they would "cancel" out because sometime we'd get a sample mean higher than the true mean sometimes lower, but is there a formal explanation as to how they cancel(usually should be some proof or explanation) for this, if not "convenient", cancellation.
Sep
22
comment Confusion on the meaning of confidence interval
i see, you want to be precise. but can you explain why is the area under the curve to the left of 72.1 is less than the area under the curve to the right of 72.1 in the graph above?
Sep
22
comment Confusion on the meaning of confidence interval
but why is the area under the curve to the left of 72.1 less than the area under the curve to the right of 72.1 in the graph above?
Sep
22
comment Confusion on the meaning of confidence interval
we should be able to assume the distribution is normal because of Central Limit Theorem, and in this case $n$ >30
Sep
22
comment Probability in flipping a coin
shouldn't the answer be $1-p-p^2-p^3-p^4$ because $1-p^4$ only excluded the possibility that all of the first 4 flips are H, we can also have HTHHH, HHTHHH, HHHTHHH, therefore those probabilities need to be subtracted as well.
Sep
22
comment Probability in flipping a coin
ok yes, you're correct. ill think about it a little bit more
Sep
22
comment Probability in flipping a coin
your answer is very insightful, but after reading them, I tend to side with the answer $1-p$ simply because we can have any gibberish after the first flip, for example, THTHTHTTH, if we want to form HHHH, we must have HHH, and because we have ensured that the first roll is not an H, we will eventually have THHH, in my suggested gibberish example, it would turn out to be THTHTHTTHHH, there we have THHH before HHHH. So $1-p$ excludes the possibility that on the first flip, we have a H, there's the answer we're looking for.