O'Reilly logo

Industrial Statistics with Minitab by Xavier Tort-Martorell Llabres, Lluis Marco Almagro, Pere Grima Cintas

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

25.3 Wear

To study the possible relationship between the wear and tear of a cutting machine and both its rotation speed and the material it was made of, the data of file WEAR.MTW are provided:
Col. Content
C1 Wear and tear after 8 hours of operation (in tenths of a mm)
C2 Rotation speed (in rpm)
C3 Type of steel (encoded as 0 and 1)
The aim is to find an equation that explains the wear and tear as a function of both variables available.

As always, we start with an exploratory analysis of the data:

Graph > Matrix Plot > Matrix of plots: Simple

nc25uf020.eps

Looking at the Matrix Plot, we can rule out the presence of anomalous values. Regarding the relations among the variables, we see that a higher speed is associated with a major wear, and that material 1 wears out more than material 0.

In this case, it is also a good idea to draw a scatterplot of wear versus speed stratified according to the material.

Graph > Scatterplot: With Groups

nc25uf021.eps
nc25uf022.eps

We can clearly see the relation between wear and speed as well as that material 1 wears out more than material 0. We compute the equation of the regression model:

Stat > Regression > Regression

Since the type of material is a categorical ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required