## Calendar

Jun 19

... there are no simple 'right' answers for most web design questions (at least not for the important ones). What works is good, integrated design that fills a need--carefully thought out, well executed, and tested.

`-- Steve Krug, Don't Make Me Think, p. 136`

## Featured chapter

Read the fascinating history of Wearable Computing, told by its father, Steve Mann

## Latest books

The Social Design of Technical Systems: Building technologies for communities

The Encyclopedia of Human-Computer Interaction, 2nd Ed.
by Mads Soegaard and Rikke Friis Dam

# Mark McMulkin

### Publications by Mark McMulkin (bibliography)

1992

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McMulkin, Mark (1992): Description and Prediction of Long-Term Learning of a Keyboarding Task. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 276-280.

The goal of this study was to determine an equation ("learning function") that describes long-term learning of a new keyboard. Five subjects learned 18 characters on a chord keyboard, then improved keying speed by inputting typical numeric keypad text for about 60 total hours. Their performance, in characters typed per minute, was recorded for every trial. Of the various functions that were considered to describe performance, the best fitting equation was a Log-Log relationship of the form CPM{sub:i} = e{sup:b{sub:0}}T{sub:i}{sup:b{sub:1}}, where CPM{sub:i} is the performance in characters per minute on the i-th trial (T{sub:i}) and b{sub:0} and b{sub:1} are fitted coefficients. A second goal was to investigate how many trials of performance are needed before the entire learning function can be determined. The coefficients of the Log-Log function were determined using only the first 25, 50, 75, 100, 125, 150, 175, and 200 of the initial performance points (out of about 550 total actual data points). The mean squared error (MSE) was calculated for each of these fits and compared to the MSE of the fit using all points. From the results of MSE data, it appears that at least 50 performance data points are required to reduce the prediction error to an acceptable level.

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Woldstad, Jeffrey C., Rockwell, Christopher J., Johnson, Christian A., McMulkin, Mark and McMahan, Paul B. (1992): Isometric Strength Capability for a Vertical Wheel-Turning Task. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 664-668.

This paper reports on the measured isometric strength capability of 125 male and 125 female college students performing a one-handed wheel turning task. Three measures of isometric strength were used: (1) a three-second average of steady state levels taken from a six-second exertion, (2) the largest value (peak) from the same six-second exertion, and (3) a maximum exertion level taken from a separate "ramp-to-peak" exertion. Standardized whole-body strength measurements for the legs, arms, and torso as well as grip strength were also taken for each subject. The results presented in this paper demonstrate average isometric wheel turning strengths (torques) ranging from 109 to 152 N-m for males and 66 to 91 N-m for females, depending upon the strength measure used. The three strength measures were highly correlated, but produced significantly different estimates of strength. The three-second average produced the lowest estimate while the ramp-peak value produced the highest. Wheel turning strengths were also highly correlated with the standardized whole-body strength measures and with grip strength. Multiple regression models developed to predict wheel turning strength using these values accounted for 69 to 71 percent of the variation in the measures. The model results also suggest that grip strength plays an important role in determining wheel turning strength capability.

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## Calendar

Jun 19

... there are no simple 'right' answers for most web design questions (at least not for the important ones). What works is good, integrated design that fills a need--carefully thought out, well executed, and tested.

`-- Steve Krug, Don't Make Me Think, p. 136`

## Featured chapter

Read the fascinating history of Wearable Computing, told by its father, Steve Mann

## Latest books

The Social Design of Technical Systems: Building technologies for communities

The Encyclopedia of Human-Computer Interaction, 2nd Ed.
by Mads Soegaard and Rikke Friis Dam