Question

what is confidence limits?

Answer 1

the limits whereby you are confident that you have the mean someplace inbetween

Answer 2

in other words, im pretty sure its some wheres between here and here

Answer 3

well there's a question, lemme type it out

Answer 4

a 95% confidence interval says that 95% of the means from the data will be accurate

Answer 5

yea the question asks something about 95% confidence limits... i'll type it out anyways

Answer 6

In a large city A, 20% of a random sample of 1000 school children had an eye defect. in another large city B, 15% of a random sample of 2000 school children had the same eye defect. Is the difference between the 2 proportions significant? Obtain 95% confidence limits for the difference in the population proportions.

Answer 7

z = something ... ill have to read up on it to refresh the memory

Answer 8

http://www.stat.sc.edu/~hendrixl/stat205/Lecture%20Notes/Confidence%20Interval%20for%20the%20Population%20Proportion.pdf

might be helpful

Answer 9

I have no idea what they want me to do with that question... i'm just trying my hands out on as many algebra questions i can get, then i'll move on to calculus... http://www.cramster.com/algebra-practice-problems-p25-1-3-0-0-0-0-3-cpi2-0.aspx

Answer 10

i've never met this kind of problem.. my very first so it'll be good to learn something new

Answer 11

it might be that we make 2 distributions and where they overlap is a solution

Answer 12

well how do u construct such a distribution with the information given,... what's your virtical axix, what's your horzontal... my best guess is that this even has nothing to do with x-y axes...

Answer 13

the vertical axis is just the base; its the "x axis"

the verticals are you means of each distribution; or in this case the proportions i believe

Answer 14

i see... thanks :)

Answer 15

i never reallt got into knowing these doubled up curves; otherwise id have some idea what to do :) good luck tho

Answer 16

sure :) thanks

Answer 17

We might want to construct a confidence interval for the difference between the two proportions. The appropriate formula is:

\[(p_1-p_2)\pm Z_{a/2}\sqrt{\frac{p_1q_1}{n_1}+\frac{p_2q_2}{n_2}}\]

found this one google

Answer 18

how to determine if its p1 or p2 tho I aint got a notion

Answer 19

I still have no idea where to move on from here but i'm sure if i read about it i should be able to handle it :)

Answer 20

In a large city A, 20% of a random sample of 1000 school children had an eye defect.

p1 = 0.2, q1 = the rest ... 0.8 ; n1 = 1000


in another large city B, 15% of a random sample of 2000 school children had the same eye defect.

p2 = 0.15 , q2 = the rest ... 0.85 ; n2 = 2000


Is the difference between the 2 proportions significant?

..............dunno yet

Obtain 95% confidence limits for the difference in the population proportions.

the zscore for 95% is: 1.96

this gives us:

\[|0.2 - 0.15|\pm1.96\sqrt{\frac{0.2*0.8}{1000}+\frac{0.15*0.85}{2000}}\]

thats what I come up with :)

Answer 21

well with the comments u made in addition to the mathematical statements plus the formula... that does make sense but to fully understand this whole topic, i'll still require to read, if anything comes up, i'll let you know :)

Answer 22

highest and lowest limits: in statistics, the highest and lowest values of a confidence interval

Answer 23

http://www.acastat.com/Statbook/ztest2.htm

good luck :)