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Chapter 11: Problem 30

Two different underground pipe coatings for preventing corrosion are to be compared. The effect of a coating (as measured by maximum depth of corrosion penetration on a piece of pipe) may vary with depth, orientation, soil type, pipe composition, etc. Describe how an experiment that filters out the effects of these extraneous factors could be carried out.

Short Answer

Expert verified
This problem could be addressed by designing a controlled experiment where the factors such as depth, orientation, type of soil and pipe composition are held constant while the pipe coatings vary. Pairs of identically situated pipes can provide an experimental and control group exclusively differing in terms of the pipe coating. Observations made on the maximum depth of corrosion on these pipes can then be used to determine the most effective coating.

Step by step solution

01

Identifying factors

Identify all the factors that might influence the effectiveness of the pipe coatings. These factors include depth, orientation, soil type, and pipe composition.
02

Control the factors

Control these factors so they do not influence the experiment. An ideal solution would be to use pairs of identical pipes under identical conditions (same depth, same orientation, same soil type, and made from the same material), but with each member of the pair coated differently. By pairing pipes in this way, you remove the effects of the factors like depth, orientation, soil type, and composition from the equation.
03

Carry out the experiment

Carry out the experiment over a chosen time period, and measure the maximum depth of corrosion on each pipe in the pairs at the end of the period.
04

Analysing data

Compare the results between the coatings in each pair to filter out the effects of the other factors. If one coating consistently shows less corrosion than the other across multiple pairs, you can determine that coating is more effective at preventing corrosion. The key point here is that each pair acted as its own control group, eliminating the confounding effects of depth, orientation, soil type, and pipe composition.

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