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Research Methods in Human Factors
Published in Robert W. Proctor, Van Zandt Trisha, Human Factors in Simple and Complex Systems, 2018
Robert W. Proctor, Van Zandt Trisha
As implied by the name, descriptive statistics describe or summarize the results of research. One concept that is fundamental to descriptive statistics is that of the frequency distribution. When we obtain many measurements of a variable, we can organize and plot the frequencies of the observed values. For example, if we have a group of people estimate the mental workload imposed by a task on a scale of 1–7, we can record the number of people who responded with each value. This record of the frequency with which each score occurred is a frequency distribution. A frequency distribution often is plotted in the form of a frequency polygon, as is shown in Figure 2.3. A relative frequency distribution, also shown in the figure, displays the same plot on the scale of the proportion (or percentage) of times that each score was observed. We can describe a score in terms of its percentile rank in the distribution. A percentile is a point on a measurement scale below which a specified percentage of scores falls. The percentile rank is the percentage of scores that falls below that percentile. We use percentile ranks for, among other things, creating tables of anthropometric data and applying these data in the design of equipment for human use.
Miscellaneous Algorithms
Published in Nazmul Siddique, Hojjat Adeli, Nature-Inspired Computing, 2017
Ranking and movement: The search agents are ranked using percentile ranking. A percentile rank is the percentage of scores that fall below a given score. The percentile of the i-th data point in a sorted data of N samples is defined by pct(Xi)=100×i−0.5N where pct(.) denotes the percentile function.
Advanced Project Planning and Risk Managemen
Published in Timothy J. Havranek, Modern Project Management Techniques for the Environmental Remediation Industry, 2017
The median is the point in a frequency histogram (or probability density function) that partitions the total set of measurements into two sets equal in number. The median is the middle point of all observations. The median can be determined by counting from either end of a frequency histogram until half of the values are accounted for. Percentile rank is related to the concept of the median. The median could also be called the 50th percentile rank.14 In a similar fashion, the 90th percentile rank would be that point for which the cumulative frequency (probability) is 90%.
Global levels of fundamental motor skills in children: A systematic review
Published in Journal of Sports Sciences, 2021
Lisa E. Bolger, Linda A. Bolger, Cian O’Neill, Edward Coughlan, Wesley O’Brien, Seán Lacey, Con Burns, Farid Bardid
TGMD-2 data can also be used to derive mean percentiles and age equivalents. Mean percentiles, or percentile rank, represent the proportion of the normative sample who achieved a value equal to or below the associated score. For example, a percentile of 60 means that 60% of the normative sample scored less than or equal to the performer’s score. Age equivalents use subtest scores to provide an estimated developmental age based on a child’s performance (Ulrich, 2000).