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This paper reviews the literature relating to concepts and definitions of productivity, utilization, and efficiency. From an analysis of these concepts and definitions, the author derives two unifying formulae, the first relating these factors to one another and the second adding in a quality factor. System improvement strategies are then discussed based on these two equations.

The purpose of this paper is to demonstrate application of the Taguchi method to determine the optimum level of three important parameters (factors) related to the use of a mobile phone for the text message entering task, namely illumination level, noise level and mobile angle that maximizes the performance of mobile phone users.

Three levels of each parameter as available in the literature, except for the mobile angle, were considered. The design of the experiment, as proposed by Genichi Taguchi, was used to conduct nine experiments. A total of 30 male subjects participated in the experimental study. The text message entry task, in the form of Arabic text, was presented to the participating subjects and their performance, measured in terms of mean number of characters entered per minute, was recorded. The signal‐to‐noise (S/N) ratio and the analysis of variance (ANOVA) were employed to investigate the users' performance. Finally, a confirmation test was conducted to verify the validity of the results.

Results showed that, at the illumination level of 475 lux, noise level of 45 dB(A), and mobile angle of 70 degrees, the subjects were quite comfortable, efficient and entered the maximum number of characters in the mobile phone per minute. The noise was found to be the dominant parameter with a contribution of 95.53 percent towards the laid down objective followed by mobile angle, 3.25 percent and illumination level, 0.66 percent.

To the best of the authors' knowledge no study has been conducted in the past to investigate the effect of these parameters on the performance of the mobile phone users. In addition, no attempt has yet been made to find the optimal level of these parameters from a text‐entering viewpoint. The paper represents original research and in the authors' opinion carries significantly important values as it provides new information for those involved in the design of the mobile phone environment.

The purpose of this paper is to demonstrate application of the Taguchi method‐based conceptual signal‐to‐noise (S/N) approach and Pareto analysis of variance (ANOVA) to determine optimum level of three important factors related to mobile phone conversation during driving, namely time of drive (day or night), distance between cars, and mobile phone call duration that minimizes drivers' reaction time (RT) in braking response.

Three levels of each factor based on the experience, are considered in the present study. The design of experiment, in the form of an L₁₈ orthogonal array, as proposed by Genichi Taguchi is used to conduct 18 experiments. A total of 27 young male subjects participated in the experimental study. The experimental task involved pressing the brake pedal of the car by the driver upon seeing another car in front while the driver is talking on a mobile phone. Drivers' performance, measured in terms of RT in braking response, is recorded. Conceptual S/N ratio and Pareto ANOVA are employed to investigate the drivers' performance.

Results show that within the test range, drivers' performance, i.e. RT in braking response is optimum (minimum) when they performed the driving task at day time, distance between cars is long (20 meters), and mobile phone call duration is short (30 seconds). Mobile call duration is found to be the dominant parameter with a percentage contribution ratio of 41.882 percent towards the laid down objective followed by time of driving, 32.003 percent and distance between cars, 1.353 percent.

This paper provides valuable information to the drivers with respect to the use of optimum level of these factors in order to minimize their RT in braking response.

To the best of the authors' knowledge, no study has been conducted in the past to investigate the effect of these factors on the performance of drivers when they use mobile phones for conversation during driving. In addition, no attempt has yet been made to find the optimal level of these factors from drivers' performance in braking response view point. This paper is an original research work of authors and in the opinion it carries significantly important values as it provides new information to the persons who talk on mobile phones during driving.

Total quality management is now an established and widely used management process. One of its associated features is the application of statistical quality control techniques. These have been applied to both manufacturing and service industries. This paper presents an application of this methodology to the area of human performance evaluation in a service industry. It describes the data, method of their collection, their analysis, and a subjective evaluation criterion developed to evaluate the performance.