Natural Resource Biometrics

t distributions

Figure 1. Example of an t distribution illustrating the critical value for an α = 0.05, df = 30, 2-tailed.

Figure 2. Example of an t distribution illustrating the critical value for an α = 0.05, df = 30, 1-tailed.

For table of t critical values .

In Excel® to look up a table number use:

=T.INV.2T(probability, degrees of freedom)

Example:

=T.INV.2T( 0.05, 29 )

Which will produce:

2.04523

Also See:

Chapter 9 - Significance of a Difference between Two Means pages 108-124 in:

Phillips, J. L. 2000. How to think about statistics. W. H. Freeman and Co. New York. 202 pp. ISBN 0-7167-3654-3

Chapter 9 - Two-Sample Hypotheses pages 126-130 in:

Zar, J. H. 2007. Biostatistical Analysis. Prentice-Hall, Inc. Englewood Cliffs, New Jersey. 718 pp.