Inverse of Student’s t Probability Lower Tail

If you know the lower tail probability, P, and you want to calculate t, enter the degrees of freedom (df1), followed by Æ, then P. Press ]oIto calculate t.

Figure 14

Example

A hypothesis test requires a critical t-value from the Student’s T distribution with 26 degrees of freedom. Find the t-value for a lower tail probability of .05.

Table 12-22

Example calculating the t-value (lower tail)

 

 

 

 

 

 

 

 

Keys

 

Display

Description

 

 

 

 

 

GS]oI7:V4

 

and the probability, and

 

 

 

-1.705618

Enter degrees of freedom

 

calculates the lower tail

 

t- value.

 

 

or, using Æ:

 

 

 

GSÆ7:V]oI

Returns the same results.

 

 

 

Figure 15

Figure 16

132 Statistical Calculations