The T distribution (sometimes called Student’s T distribution) is actually a
set
of distributions, differentiated by the degrees of freedom (df). Take a
look at
a traditional textbook T table, and you’ll actually find many T
tables, which can be a little overwhelming.
Instead of poring over tables,
you can use a TI 83 graphing calculator to assist you in finding T
distribution values. You might be asked to
find the area under a T curve, or
(like Z scores), you might be given a certain area and asked to find the T
score.
Sample problem: Find the area under a T curve with degrees of freedom 10
for P( 1 ≤ X ≤ 2 ).
Step 1: Press to select tcdf(.
Step 2: Enter the lower, and upper bounds, and the degrees of freedom:
Your screen should now read tcdf(1,2,10)
Step 3: Press . The answer is .133752549, or about 13.38%.
You can perform linear regression with a TI-83 in the time it takes you to
input a few variables into a list. Linear regression
will only give you a
reasonable result if your data looks like a line on a scatter plot, so before
you find the equation for a linear regression line
you may want to view the
data on a scatter plot first. See the Graphs chapter in this book to find out
how to create a scatter plot.
Sample problem: Find a linear regression equation (of the form y = ax + b)
for x-values of 1, 2, 3, 4, 5 and y-values of 3, 9, 27, 64, and 102.
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