p-value

p-value is used in Hypothesis Testing. You work out the test statistic and determine the chance that your result (or a worse one) could be due to chance. A low p-value means the Hypothesis is true. CalGraph will calculate the p-value.

How you do this depends on the hypothesis you are testing.

One-tailed Hypothesis Test about Mean or Proportion

Calculate the test statistic (z  or  t). If it is negative, make it positive.

If your data have the Normal Distribution, click Statistics and then Normal Distribution. In the first box, type your  z, in the second type 100. Click on Calculate. The value in the grey box on the right is the p-value.

If your data have the Student's  t  Distribution, click Statistics and then  T Distribution. In the first box, type your  t, in the second type 100. Type the Degrees of Freedom in the D.F. box. Click on Calculate. The value in the grey box on the right is the p-value.

A detailed example of a one-tailed hypothesis test using the T Distribution.

Two-tailed Hypothesis Test about Mean or Proportion

Calculate the test statistic (z or t). If it is negative, make it positive.

If your data have the Normal Distribution click Statistics and then Normal Distribution. In the first box, type your z, in the second type 100. Click on Calculate. Multiply the value in the grey box on the right  by two to get the p-value.

If your data have the Student  t  Distribution click Statistics and then  T Distribution. In the first box, type your z, in the second type 100. Type the Degrees of Freedom in the D F box. Click on Calculate. Multiply the value in the grey box on the right by two to get the p-value.

Hypothesis Test about Standard Deviation, Variance or Goodness of Fit

Calculate the test statistic ( c2 )

Click on Statistics and then Chi Square Distribution.

Type in your test statistic in the X1 box and 1000 in the X2 box. Type the Degrees of Freedom in the D.F. box and hit Calculate. The p-value is now in the grey box on the right, the Probability.

Hypothesis Test about 2 Variances or Analysis of Variance  (ANOVA)

Calculate the test statistic (F)

Click on Statistics and then F Distribution.

Type your test statistic in the F1 box and 999999999 in the F2 box. Type the first Degrees of Freedom in the D.F.1 box and the second in the D.F.2 box.

Click Calculate. The p-value is in the grey box.