Question

Hey, is there anyone that can help me with Stats?

Answer 1

The problem im having is that I don't know how to start this. All that's given to me is a table, a Pop mean of 222, N = 11, Alpha = .01. How would i start doing problem?

Answer 2

it depends on what it is you are looking for ...

Answer 3

Oh! sorry, i'm looking for a difference between the levels my group (the table im given) and the pop mean

Answer 4

so the difference between some table value x and the mean is: x-mean?

Answer 5

if you can post a picture of the problem to avoid any errors in transmission, that would be helpful

Answer 6

Will do, one second

Answer 7

so its pretty much a hypothesis test to determine if theres a difference or not between the means

Answer 8

Ho: mu1 - mu2 = 0
Ha: mu1 - m2 not= 0

Answer 9

i know this might sound like a stupid question but just for clarification, when doing a T test, i should always declare it in that format, right? mu1 - mu2 = 0 means the same as "mu1=mu2"

Answer 10

correct

Answer 11

how you define it should match your material :) but both ways are equivalent statements

Answer 12

Another quick question, df = 11 + 11 + 2. I figured the second N (of the population) to be 11 also, right?

Answer 13

dF eh ... does your material give you the simpler version or the more complicated version?

Answer 14

Simple I presume. df = n1 + n2 + 2

Answer 15

I put 11 because the total number for the problem are 11, I just don't know how to go about getting the second n.

Answer 16

we dont have 2 sample means do we?

Answer 17

and its -2 of we were comparing the means between 2 samples ...

Answer 18

Brb, one second, need to look over my notes, just realized that I'm totally looking at the wrong test for the information that I am given

Answer 19

im thinking since this isnt a pooled thing ....
\[t=\frac{\mu_1-\mu_2}{\sigma/\sqrt n}\]

Answer 20

Yep, that's the one i just found. wow i feel stupid. I don't know i was so set on using a test that compares things when im only given one piece of information

Answer 21

Would you mind checking my work once i'm done to make sure I did it right?

Answer 22

sure, i need the practice :)

Answer 23

by the way, do we have a table to work with or a stats calc like a ti83?

Answer 24

Ah, a table. I can send you a picture of that too. I hit a slight bump, can you set me straight? the formula you gave above has a Mu1 and Mu2, the formula given to us in lecture is \[t = \frac{ X - \mu }{ s /\sqrt{n} }\] *X-Bar* no X. What in the equation is what?

Answer 25

X = sample mean, u = pop mean

Answer 26

s is the sample standard deviation and n is the sample size

Answer 27

Given the table, I took the average of the cholesterol = 209.90. This is the X-bar correct?

Answer 28

yes, 209.91 is what im using

Answer 29

http://www.wolframalpha.com/input/?i=mean+%7B265+160+163+210+210+226+231+218+249+197+180%7D

Answer 30

What are you using for s?

Answer 31

havent you calculated it yet?

Answer 32

http://www.wolframalpha.com/input/?i=standard+deviation+%7B265+160+163+210+210+226+231+218+249+197+180%7D

:)

Answer 33

So, -12.9/10.03 = -1.24. which falls within the crit value = reject

Answer 34

\[\sum(x-\mu)^2\]
\[\sum(x^2-2x\mu+\mu^2)\]
\[\sum x^2-2\mu~\underbrace{\sum x}_{=\mu}+\sum\mu^2\]
\[\sum x^2-2\mu^2+\sum\mu^2\]
\[\sum x^2-\mu^2\]
just in case you didnt have a shortcut formula ...

Answer 35

http://www.wolframalpha.com/input/?i=%28209.91-222%29%2F%2833.294%2Fsqrt%2811%29%29

out t stat is going to be about: -1.2044

Answer 36

this doesnt tell us much in the way of a solution yet. its just what we use to determine a p-value to compare with. unless you know of the t stat to compare with

Answer 37

unless you know what the t boundaries are for in the distribution setup, we need to take this futher