Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Degrees of Freedom

  1. Feb 18, 2010 #1
    In the Chi-square test, my textbook says that degrees of freedom are the number of independent variables minus one so df = n - 1

    does this mean that that n is equal to the number of observed values from the equation aka the number of times I've added together the numbers?

    sum [(O-E)^2]/E

    Is there an instance where it isn't equal to the number of observed values I have?

    (there's an example in my book (but no answer) with an experiment with observed values of 2 trials of genetic crosses where observed in
    trial 1 was 0.5
    trial 2 was 0.3
    but both of these values were measuring the same variable which was heterozygosity. The expected value is 0.8. Does this mean the df = 1? or is it 0 since there is only 1 independent variable?)

  2. jcsd
  3. Feb 23, 2010 #2
    df=n-1, n means number of the random variables, in this case n is the number of trials. df=n-1=2-1=1
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Degrees of Freedom
  1. Degrees of Freedom (Replies: 25)