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degrees of freedom

f Tue 03 May 2011 02:21:00 No.2983642 View View Reply Original Report

Quoted By:

how do you factor in degrees of freedom to get the critical value?

Anonymous

Anonymous Tue 03 May 2011 02:25:00 No.2983662 Report

Quoted By: >>2983671

Sample size minus one.

Anonymous

Anonymous Tue 03 May 2011 02:26:00 No.2983671 Report

Quoted By:

>>2983662
this.

f Tue 03 May 2011 02:32:00 No.2983691 Report

Quoted By:

how does that involve the alpha level though? i have the alpha level and i have the degrees of freedom but i don't understand how i involve the degrees of freedom to get a different score than the normal 1.96

f Tue 03 May 2011 02:41:00 No.2983753 Report

Quoted By: >>2983781

so for instance here they're telling me that i have an alpha level of .05 so the t score 1.96, the degrees of freedom in this case are the n size 1 plus n size 2 minus two and it equals 21. which somehow turns into a critical value of 2.080. how did he get to that, what did he do?

Anonymous

Anonymous Tue 03 May 2011 02:43:00 No.2983761 Report

Quoted By:

you sue the t table, not a normal table

Anonymous

Anonymous Tue 03 May 2011 02:46:00 No.2983770 Report

Quoted By:

Uh are you referring to normal distribution and the Student t-distribution?

The normal distribution's z-value is the same as the t-value as you approach a huge ass sample size.

What you do is look at the chart:

http://www.unc.edu/~nielsen/soci708/statistical_functions/ips6e/ips6e_table-d.pdf

Look at the first column. That's your sample size minus 1 (n-1). Find the confidence value at the bottom. Scroll up the columns and across the row to find the appropriate t-value.

n = 25
Confidence value: 95%
t-value: 2.064

Notice under the 1000 d.f. column there's a z* where all the t-values approach the z critical values.

Anonymous

Anonymous Tue 03 May 2011 02:48:00 No.2983781 Report

Quoted By:

>>2983753

That's d.f. = 21,\alpha = 0.025.

f Tue 03 May 2011 02:52:00 No.2983799 Report

Quoted By:

ok, i forgot i had to use a chart. lol. sorry about that, thanks a lot guys you've been a huge help. i suck at math but i have to take statistics to get my bachelors, i have no idea what i'm doing some of the time.

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