how do you find the p value in statistics
isnt" p" the polulation, or portion or sample size
can you help me solve this ...
The alternative hypothesis for the difference between two means is Ha:µ1-µ2 ≠ 0. For this test, the test statistic, z is 2.53. What is the p-value for the test?
p is the confidence level at which the test value equals the critical value
ok how can i apply this to the question i posted above?
difference between 2 means is a 2 tailed test
find the area under of z between -2.53 and 2.53
under the standard normal curve for -2.53 < z < 2.53
im sorry, how do we find the area under z?
from a standard normal table
http://statistics.laerd.com/statistical-guides/img/normal/normal-table-large.png
alright thanks, i have no idea how any of this works. im doin the work for a friend.
the area to the right of z=2.53 is (1-.9943) = .0057 the p value is twice that, p = .0114
wow thanks so much!!! i really appreciate it. would you be able to help me with one more question?
sure
A study by a corporation revealed that the mean weekly salary for managers in department A was $1,500 with a standard deviation of $100 (sample size = 64) while the mean weekly salary for managers in department B was $1,275 and a standard deviation of $150 ( sample size = 81 ). Construct the 95% confidence interval for the difference between the mean salaries for managers.
i even have four choices for this one.. ill send them right now
(167.3, 234.2 ) (202.3, 227.1) (104.9, 167.3 ) (184.2, 265.8)
alpha = 1 - .95 = .025
df = 64 - 1
t (alpha/2) = .679
from the table http://3.bp.blogspot.com/_C6375WoyYP0/THVqQkJRqbI/AAAAAAAAASU/ML7g-OPPgug/s1600/Student-t-table.png
actually because it's multiple choice, you can just pick the answer which has an average of (1500 - 1275) = 225. That's answer D
(184.2, 265.8) ? that's what we were thinking! wow thanks
i also read the table wrong
t (alpha/2) = 2.000
(1500 - 1275) + 2*Sqrt[100^2/64 + 150^2/81] and (1500 - 1275) - 2*Sqrt[100^2/64 + 150^2/81] which is close to answer D
ok thanks so much.. thats what i was going with.. there is one more with the 95% interval.. would you mind helping again? if not its ok we appreciate it
Suppose you have a sample selected from a normally distributed population and the sample mean is 64.5 and the sample standard deviation is s = 7.6. Find a 95% confidence interval for µ assuming n=9.
there are also choices for this.... (53.78, 60.73) (58.66,70.34) (61.47, 67.21) (62.16, 72.57)
alpha = 1 - .95 = .05 again
look up t from table with alpha/2 = .025 and df = 9 -1 = 8
t (alpha/2) = 2.306
the E = 2.306*7.6/Sqrt[9] = 5.84187
64.5+5.84187=70.3419 64.5-5.84187=58.6581 answer B
thank youu sooo muchhh!!
i got those charts from elementary statistics 9ed by mario triola
ok great gonna save them to my computer so that i have it for the future
you want the whole book?
no you helped us enough. i really appreciate it.. i actually have one more question- would you be willing to help.. its my last one
The mean fill of containers of sugar is 16.0 ounces with a standard deviation of 1.5 ounces. Samples of size n = 9 are taken from the population of all containers of sugar. The population values are normally distributed. Find the probability that a given sample mean will exceed 17 ounces. (Hint: See Example 6.7b in Section 6.3 of the text. Don't worry that the value of n is only 9.) Approximately 0.09 Approximately 0.05 Less than 0.02 .04
working on it
the standard deviation for the sample mean is sigma/Sqrt[n] = 1.5/Sqrt[9] = 0.5
the mean of the sample = 16
calculate z-score (17-16)/.5 = 2
find the area to the right of z=2 on standard normal table
= (1-.9772) = .0228
doesn't seem to match the answer choices
hm i wonder why. thats strange!
I'd put C and ask the teacher
ok thank you for all your help today!
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