The corresponding dataset also indicates that there are differences in the means of internet usage between genders (no further explanation of their calculation is shown at this point). The variance of internet usage (hours per week) among men is significantly greater than in women. 050, it can be assumed that the variances of the “Internet usage” variable assigned to both genders differs significantly. SPSS produces the following figure when conducting the one-way analysis of variance (select “Homogeneity of variance test” under “Options”):įigure 4: Levene test for homogeneity of varianceįigure 4 shows the Levene test.

It can therefore be assumed that the differences in the variances of the “Internet usage” variable assigned to both genders are significant. The calculated test statistic is greater than the critical value (1.77 > 1.26). 05 is selected, whereby the relevant critical value is 1.26 (see red marking in Table 2). In this example, a significance level of. The F-table shows the critical value of the significance levels. Because these degrees of freedom do not appear in the table, the critical value is taken from the nearest column or row, which is defined through smaller degrees of freedom (in this case: df1= 200 and df2= 200). In this example, the numerator degree of freedom is 346 (347-1) and the denominator degree of freedom is 304 (305-1). Table 2: Extract from an F-table (Bortz & Schuster, 2010) The answer to the question can be found with the help of a model, which in this case looks as follows: The question is examined by means of a randomly generated subsample (n = 652 adult US citizens) of the General Social Survey (GSS) of the year 2000. The F-test is summarized in three steps, which are described in the following section. This chapter explains in detail the F-test procedure based on the following question:ĭoes the variance in internet usage (in hours per week) differ between women and men? The F-test and its associated procedures are used, for example, for determining whether variance analyses meet the prerequisite of homogeneity of variance. The dependent variable should be at least ordinal scaled and normal distributed. The F-test can be used for determining whether the variances of two samples (or groups) differ from each other.

The F-test is a statistical procedure in which the test statistic is F-distributed.

Calculate degrees of freedom in spss