11.1.3 - Probability Distribution Plots

In previous lessons you have constructed probabilities distribution plots for normal distributions, binomial distributions, and \(t\) distributions. This week you will use the same procedure to construct a probability distribution plot for the chi-square distribution.

MinitabExpress  – Constructing a Probability Distribution Plot

Chi-square tests of independence are always right-tailed tests. Let's find the area of a chi-square distribution with 1 degree of freedom to the right of \(\chi^2 = 1.75\). In other words, we're looking up the \(p\) value associated with a chi-square test statistic of 1.75.

  1. On a PC: from the menu select STATISTICS > Distribution Plot
    On a Mac: from the menu select Statistics > Probability Distributions > Distribution Plot
  2. Select Display Probability 
  3. For Distribution select Chi-Square
  4. For Degrees of freedom enter 1
  5. Select A specified X value
  6. Select Right tail
  7. For X value enter 1.75

This should result in the following output:

Chi-square distribution plot made using Minitab Express; degrees of freedom equal 1; the area to the right of a chi-square value of 1.75 is 0.185877

Video Walkthrough

Select your operating system below to see a step-by-step guide for this example.

Example: Area to the Right of Chi-Sq = 6.25, df=3 Section