The article “Factorial Experiments in the Optimization of Alkaline Wastewater Pretreatment” (M. Prisciandaro, A. Del Borghi, and F. Veglio, Industrial Engineering and Chemistry Research, 2002:5034–5041) presents the results of several experiments to investigate methods of treating alkaline wastewater. One experiment was an unreplicated \(2^4\) design. The four factors were A: concentration of sulfuric acid, B: temperature, C: time, and D: concentration of calcium chloride. The outcome variable is the amount of precipitate in \(\mathrm {kg/m^3}\). The results are presented in the following table.

a. Estimate all main effects and interactions.

b. Which effects seem to be larger than the others?

c. Assume that all third- and higher-order interactions are equal to 0, and add their sums of squares. Use the result in place of an error sum of squares to compute F statistics and P-values for the main effects. Which factors can you conclude to have an effect on the outcome?

d. The article described some replicates of the experiment, in which the error mean square was found to be 1.04, with four degrees of freedom. Using this value, compute F statistics and P-values for all main effects and interactions.

e. Do the results of part (d) help to justify the assumption that the third- and higher-order interactions are equal to 0? Explain.

f. Using the results of part (d), which factors can you conclude to have an effect on the outcome?

Equation Transcription:

Text Transcription:

2^4

kg/m^3

PREVENTING CHRONIC DISEASE ● Evidence-based approach ○ Engaging the community is assessment and decision making ○ Using data and information systems systematically ○ Making decisions on the basis of the best available peer- reviewed evidence ○ Applying program-planning frameworks ■ Based on health-behavior theory ○ Conducting sound evaluation ○ Disseminating what is learned ● Mixes science-based interventions with community preferences for improving population ● EBPH integrates best available research evidence, practitioner expertise, and the needs and preferences of those who will be affected by the intervention ● Public health decision making is a complex process ○ Sometimes lack a comparison group ● Formal training varies more than training in medicine ○ No single licence certifies a public health practitioner ● Interventions often implemented on a political or media pressure basis ○ Lack of funding Need for Evidence-Based Public Health (EBPH) ● Mission of Healthy People 2020 = to strengthen policies and improve practices that are driven by the best available evidence and knowledge ● Because formal health training is lacking, on the job training and skills development are needed ● Core Competencie