11.2 ANOVA with a Single Factor

Example 11.1: The technicians of a paper processing company decide to carry out an experiment in order to study which variety of tree produces less contents of phenols in the waste of paper pulp. The following data represent the quantities obtained (in %).
Unnumbered Table
Do any of the tree varieties produce more phenols?

This problem deals with the comparison of the means of three treatments, being ‘Variety of tree’ the only factor under study.

If we place the data for each type of tree in a different column, we have to proceed as shown below.

Stat > ANOVA > One-Way (Unstacked)

nc11uf002.eps
nc11uf003.eps
nc11uf004.eps

In the worksheet, both the residuals and the fitted values are stored (we checked these options in the initial dialog box).

nc11uf005.eps

If the data of the three varieties of trees are stored in one single column, we have to choose the following.

Stat > ANOVA > One-Way

All options and results ...

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