Question

An article presents a study comparing the effectiveness of a video system that allows a crane operator to see the lifting point while operating the crane with the old system in which the operator relies on hand signals from a tagman. Three different lifts, A, B, and C were studied. Lift A was of little difficulty, lift B was of moderate difficulty, and lift C was of high difficulty. Each lift was performed several times, both with the new video system and with the old tagman system. The time (in seconds) required to perform each lift was recorded. The following table present the mean, standard deviation, and sample size.

	Low Difficulty
	Mean	Standard Deviation	Sample Size
Tagman	48.29	2.19	14
Video	47.35	2.65	40

	Moderate Difficulty
	Mean	Standard Deviation	Sample Size
Tagman	68.33	6.26	12
Video	58	5.59	24

	High Difficulty
	Mean	Standard Deviation	Sample Size
Tagman	109.71	17.02	17
Video	84.52	13.51	29

Can you conclude that the mean time to perform a lift of low difficulty is less when using the video system than when using the tagman system? Find the P-value and state a conclusion.

Answer 1

Let sample 1: Tagman

sample 2: video

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Answer: The p-value = 0.1197

Conclusion: There is no evidence to conclude that the mean time to perform a lift of low difficulty is less when using the video system than when using the tagman system.