Question

A three factor factorial design was run to find lead level by using flame atomic absorption spectrometry. The data are provided in the following table. ST is the shaking time in minutes. The three factors are ST (shaking time in minutes), pH, and RC (reagent concentration). For RC the low is 5 x 10-6 and high is 5 x 10-5. Shaking time has a low of 10 minutes and a high of 30 minutes. There are 16 runs total for this design Rep is short for replicate. Replicate is not a factor in the design. Ignore it when you put in your data.

Factors			Lead Recovery (%)
ST	pH	RC	Rep 1	Rep 2
-1	-1	-1	39.8	42.1
1	-1	-1	51.3	48.0
-1	1	-1	57.9	58.1
1	1	-1	78.9	85.9
-1	-1	1	78.9	84.2
1	-1	1	84.2	84.2
-1	1	1	94.4	90.9
1	1	1	94.7	105.3

Use minitab and show steps.

a. Construct an ANOVA table.

b. Conduct the ANOVA.

c. Analyze the residuals.

d. Interpret results.

Answer 1