In their report to the Senate Public Works Committee, Texaco Inc. presented a dataset as evidence that the Octel filter, developed by Associated Octel Company for reducing air pollution, was at least as good as a standard silencer in controlling vehicle noise levels. The findings were based on a 2-way factorial experiment with 6 replications. The two factors are:

? TYPE - type of filter (1 = standard silencer, 2 = Octel filter)

? SIZE - vehicle size (1 = small, 2 = medium, 3 = large).

The response variable (NOISE) is the noise level reading in decibels. The complete dataset is detailed below:

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