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Estimating time needed to complete a task. In project
Chapter 15, Problem 57E(choose chapter or problem)
Estimating time needed to complete a task. In project management, a key concern is the length of time it takes to perform a certain task. Managers have found that estimating the time in a series of short segments generally leads to an underestimation of the total time. This theory was tested in a study published in Applied Cognitive Psychology (Vol. 25, 2011). Each in a sample of 10 subjects was asked to visualize walking a familiar route for about 20 minutes. Subjects were then asked to provide an estimate of the distance walked in several shorter time segments (e.g., in 45-second intervals) until the destination was reached. The total walking time was then determined by adding up the time segments required to reach the destination. All subjects estimated total walking time (in minutes) under each of four time-segment conditions: 45-second intervals, 2-minute intervals, 3-minute intervals, and 5-minute intervals. The data (simulated from information provided in the article) are listed in the table on the next page. The researchers want to know if the distribution of walking times differs for the four time segments.
a. Explain why the data should be analyzed using Friedman’s test.
b. A Minitab printout of the analysis is shown below. Locate the test statistic and p-value on the printout.
c. Using \(\alpha = .01\), what conclusion can you draw from the test?
Questions & Answers
QUESTION:
Estimating time needed to complete a task. In project management, a key concern is the length of time it takes to perform a certain task. Managers have found that estimating the time in a series of short segments generally leads to an underestimation of the total time. This theory was tested in a study published in Applied Cognitive Psychology (Vol. 25, 2011). Each in a sample of 10 subjects was asked to visualize walking a familiar route for about 20 minutes. Subjects were then asked to provide an estimate of the distance walked in several shorter time segments (e.g., in 45-second intervals) until the destination was reached. The total walking time was then determined by adding up the time segments required to reach the destination. All subjects estimated total walking time (in minutes) under each of four time-segment conditions: 45-second intervals, 2-minute intervals, 3-minute intervals, and 5-minute intervals. The data (simulated from information provided in the article) are listed in the table on the next page. The researchers want to know if the distribution of walking times differs for the four time segments.
a. Explain why the data should be analyzed using Friedman’s test.
b. A Minitab printout of the analysis is shown below. Locate the test statistic and p-value on the printout.
c. Using \(\alpha = .01\), what conclusion can you draw from the test?
ANSWER:
Step 1 of 3
(a)
The subjects are estimated at four different time segments, and also the data are not independent. Suppose that the data would not be normally distributed. Hence, the parametric test is not applicable. Thus, the nonparametric test, Friedman’s test, should be appropriated to analyze the data.