11.3 ANOVA with Two Factors

Example 11.2: A study is carried out to analyze whether the type of painting, among three types available, affects the hardness of a certain type of enamel. The firing of the parts is done in an oven with four trays, one above another, and with 15 parts on each. Since it can be assumed that the tray might have an influence on the result, because of its position in the oven, a blocked design is used putting five parts of each type of painting on each tray. The following hardness measures are obtained:
Unnumbered Table
Can we affirm that the type of painting affects the degree of hardness?

Notice that now we have two factors which may affect the response: the type of painting and the tray on which the parts are placed.

Place obtained values in the worksheet as indicated below:

nc11uf007.eps

Stat > ANOVA > Two-way

nc11uf008.eps
nc11uf009.eps
nc11uf010.eps
Example 11.3: The tensile strength of different pieces ...

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