An article in Talanta (2005, Vol. 65, pp. 895–899)

presented a 23 factorial design to find lead level by using flame atomic absorption spectrometry (FAAS). The data are shown in the following table.

The factors and levels are shown in the following table.

(a) Construct a normal probability plot of the effect estimates.
Which effects appear to be large?

(b) Conduct an analysis of variance to confirm your findings or part (a).

(c) Analyze the residuals from this experiment. Are there any problems with model adequacy?

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Factors Run ST pH RC 12345678 + + + 8 + | | + + | |++ Lead Recovery (%) RI R2 39.8 42.1 51.3 48 57.9 58.1 78.9 85.9 + 78.9 84.2 + 84.2 84.2 ++ 94.4 90.9 94.7 105.3