Statistics for everyone: Excel and Statistics(20), ANOVA

Excel and Statistics, everybody should know. : Contents

ANOVA

Let’s open ‘example1.xlsx’ to do ‘Anova: Single Factor’.

We call ‘one-way Analysis of variance’ or ‘one-way ANOVA’ more commonly than do ‘Anova: Single Factor’.

Specify three columns, i.e. columns 2 through 4, as the ‘input range’.

Each column is summarized as observed sum, mean, and variance, followed by the ‘ANOVA’, which is famous as the ‘ANOVA table’. With a value of p=0.041288, we come to the conclusion that we can reject the null hypothesis that the mean of the three groups is equal.

Analysis of variance (ANOVA) is an extension of the t-test, which is designed to determine whether the means of three or more groups are equal. Again, like the t-test, it assumes normality and equal variance.

Therefore, as we learned earlier, it is necessary to examine normality and equal variance using statistical tests or graphs. Also, if a p<0.05, you need a pairwise comparison to see all pairs of groups.

If the numbers in the three groups are different and the range is entered,

It adjusts the number of observations accordingly and calculates them.

Plus Alpha

Visit http://tinyurl.com/violins4explorers and upload ‘example1.csvŒ’. The data is the same as ‘example1.xlsx’. By default, ‘ANOVA or t-test’ is set, but if it is group 2, it automatically executes t-test, and if it is group 3 or more, ANOVA is automatically executed.

The ‘descriptive’ tab shows various values, such as mean or standard deviation. The ‘Shapiro p’ at the bottom shows the p-value after running Shapiro test to see if it is normally distributed. In the case of group B, p=0.0001, which is hardly a normal distribution.

The ‘analysis’ tab shows the ANOVA table.

Naturally, it is the same as the ANOVA table in Excel that we saw earlier.

‘ANOVA post hocŽ’ shows a comparison of two groups. In other words, A-B, A-C, and B-C are compared, and the P values are corrected according to multiple comparisons, and various methods can be selected. In the above case, the P value of C-A is 0.0436, which is less than 0.05, so there is a * mark.

It is recommended not to just look at the P value, but always try to plot it.

Excel and Statistics, everybody should know. : Contents

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