Surface treatment and abrasion
This diagram shows graphically a model for three factors with no interaction.
Initially the diagram shows only the mean response. Use the checkboxes to fit models with different combinations of factors.
Note how the diagram displays the two levels of Surface treatment with a green and a purple grid when its main effect is in the model.
Click the y-x and y-z buttons to rotate. The parallel lines reflect the additive nature of the no-interaction model.
Observe that using all three factors allows the mean responses to be close (but not identical) to the corresponding observed responses.
Abrasion resistance in materials is often measured by rubbing specimens against a standard abrasive and recording either the decrease in thickness or the loss in weight. The table below describes results from a factorial experiment on coated fabrics to assess the effect of three factors.
Two types of filler were used in each of 3 proportions and half of the pieces of fabric were given a surface treatment before testing. Each response measurement shown in the table below was the average weight loss (mg) from two samples after 3000 revolutions of the testing machine.
(We only combine the two replicates to simplify the diagram a full analysis would use the individual values from the separate samples.)
No surface treatment | Surface treatment | ||||
---|---|---|---|---|---|
Percentage Filler |
Filler A | Filler B | Filler A | Filler B | |
25% | 544 | 416.5 | 470.5 | 310.5 | |
50% | 642.5 | 451 | 550.5 | 268 | |
75% | 733.5 | 443 | 654 | 313 |