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Homework Help: Levene's Test for Equality of Variance

  1. Apr 9, 2005 #1
    I have just started University and we have been doing t-tests however in our Computer labs we are supposed to do the Levenes Test. I have done the levenes test from our data of males and female heights in our class. i was just wondering what a value of F = 0.001 and Sig. 0.982 would mean. the computer program we are using is SPSS. I know its about testing if the variances are the same, however i dont know what the values are telling me. Any help would be greatly appreciated.
     
  2. jcsd
  3. Apr 9, 2005 #2

    xanthym

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    Science Advisor

    Statistical tests usually involve making various assumptions about the characteristics and parameters of the population being sampled. In your case, you are performing the "t-test" to test hypotheses about 2 sampled groups. One of the assumptions made by the standard "t-test" is that the 2 populations being sampled have EQUAL VARIANCES. The purpose of the Levenes Test is to test and verify that this equal variance assumption is reasonable.

    The Levenes Test outputs 2 parameters in SPSS. The first is the F statistic value. The larger the F statistic number, the greater is the possibility the variances are different. Similarly, the smaller the F value, the greater is the probability that the variances are equal. In your case, F appears very small (which is good :smile:).

    The probability that the variances are equal are reported in the value labeled "Sig", which stands for "significance". This number is a probability between 0 and 1, and the closer it is to 1, the greater is the probability the variances are equal. In your case, the "Sig" value (0.982) is very high and indicates a high probability the population variances are equal. Knowing this, you can now use the standard parametric "t-test" (which makes the assumption of equal variances) with confidence that the variances are most likely equal.


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  4. Dec 5, 2009 #3
    Hi
    Im a lil confused here.. the thing is im getting no F value in my SPSS output. Like the the F value area is blank. What do i do?
     
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