Refer to the Human Factors study of the performance of a computerized speech recognizer, Exercise 12.26. Recall

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Refer to the Human Factors study of the performance of a computerized speech recognizer, Exercise 12.26. Recall that the researchers built a complete second-order model for task completion time (y) as a function of accuracy (x1) and vocabulary (x2).

a. Give the null hypothesis for testing whether the quadratic terms in the model are useful predictors of y.

b. The test, part a, resulted in a p-value of less than .01. Interpret this result.


Data from Exercise 12.26

A study reported in Human Factors (Apr. 1990) investigated the effects of recognizer accuracy and vocabulary size on the performance of a computerized speech recognition device. Accuracy (x1) of the device, measured as the percentage of correctly recognized spoken utterances, was set at three levels: 90%, 95%, and 99%. Vocabulary size (x2), measured as the percentage of words needed for the task, was also set at three levels: 75%, 87.5%, and 100%. The dependent variable of primary interest was task completion time (y, in minutes), measured from when a user of the recognition device spoke the first input until the recognizer displayed the last spoken word of the task. Data collected for n = 162 trials were used to fit a complete second-order model for task completion time (y), as a function of the quantitative independent variables accuracy (x1) and vocabulary (x2). The coefficient of determination for the model was R2 = .75.

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Statistics For Engineering And The Sciences

ISBN: 9781498728850

6th Edition

Authors: William M. Mendenhall, Terry L. Sincich

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