25. The article The In uence of Corrosion Inhibitor and Surface Abrasion on the Failure of Aluminum-

Wired Twist-on Connections (IEEE Trans. Components, Hybrids, Manuf. Tech., 1984: 20—25) reported data on potential drop measurements for one sample of connectors wired with alloy aluminum and another sample wired with EC aluminum. Does the accompanying SAS output suggest that the true average potential drop for alloy connections (type 1)

is higher than that for EC connections (as stated in the article)? Carry out the appropriate test using a signi cance level of .01. In reaching your conclusion, what type of error might you have committed?

(Note: SAS reports the P-value for a two-tailed test.)

Type N Mean Std Dev Std Error 1 20 17.49900000 0.55012821 0.12301241 2 20 16.90000000 0.48998389 0.10956373 Variances T DF Prob Unequal 3.6362 37.5 0.0008 Equal 3.6362 38.0 0.0008