The sample mean aproaches the real mean, and the guy paying for the study aproaches bankrupcy.

 

magician...is there a way to graph t distributions in excel?

 

Yup: the function is TDIST(x,dof,tails)

x is the critical value
dof is the number of degrees of freedom
tails is 1 for a 1-tailed test and 2 for a 2-tailed test

This function gives the distribution function, not the density function. For a 1-tailed test, it returns P(t > x), where t is a random variable with a Student t-distribution with dof degrees of freedom; for a 2-tailed test, it returns P(|t| > x). The value of x must be nonnegative; for values of x that are negative, use TDIST(x, dof, 1) = 1 - TDIST(-x, dof, 1), and TDIST(x, dof, 2) = TDIST(-x, dof, 2).

If you want the density function, you'll have to create the distribution function and differentiate with respect to x.

 

i've got all the info...what i'm looking to do is make a graph of the t-distribution curve with all the info that i have. i want to use the visual to show some students how the numbers they see correlate to the curve. kinda like...here's the data, and here's what it looks like on a curve.

i've been looking for something on the web where i can just plug some numbers in to generate a graph/curve, but so far...no luck.

 

^use minitab... download the free version for 30 days, if you like it buy it. it was a pretty good statistical software i used in my class and has many other functions we didnt even get to use in my class.. if you need help with some inputs i could probably help as i just got familiar with the software last semester.

 

http://www.minitab.com/products/minitab/de...lt.aspx?home=m4

 

I use Minitab a few times per week at work, but I didn't get much out of it in school.

Learning stats is much easier if you spring for a tutorial program called Activestats (I think that's the name) AND have minitab.