Chapter 3 What Are Design and Designing? 53 Copyright Goodheart-Willcox Co., Inc. STEM STEM Link Link Anthropometric Data Designers must ensure that furniture will be comfortable, safe, and easy to use. To achieve this, they use the principles of ergonomics and anthropometric data. This data provides average dimension of the human body in various positions, including sitting at a table, standing at a counter, and reaching a lever on a machine. For example, one of the most commonly designed pieces of furniture is a dining chair. To produce a well-designed chair, the designer must know the size of the people who will use it. These measurements can be found in an anthropometric data table (Figure A). If you look at any group of people, it is clear there is a great variation in size, weight, and strength. For example, not all the students in your class are the same height. If you were to measure the height of all the students in your class and then calculate the average (called the mean in statistics), you would be able to state whether any one individual was above average or below average height. If you then measured the height of a large group of older students, for example, you would notice that many were about the same height. But some would be much taller and some would be shorter. If you plotted a graph to show this range of heights, you would create a bell curve (Figure B). Students of the same height will measure close to the average. In anthropometric data tables this is called the fiftieth percentile. It shows that half (50%) of the students are shorter and half (50%) are taller than this mean (average). The graph also shows the fifth percentile and the ninety-fifth percentile. This shows that five percent of the students are much shorter than the average and five percent are much taller than the average. Calculating Anthropometric Data Using yourself as a model, take your own measurements and fill in a table like the one in Figure A. Then combine your information with several other classmates to determine the fiftieth percentile for height in your group. Math Goodheart-Willcox Publisher Figure A Letter Dimension 50th percentile Inches (mm) A Popliteal height (part of the leg behind the knee) 15.2 (386) B Seat length/depth 18.5 (470) C Acromial height, sitting (from top of shoulder blades) 22.1 (561) D Sitting height 33.5 (851) E Seat width 19.1 (485) F Hip width, sitting 16.3 (414) G Shoulder width 15.2 (385) E F G D A B C Bukavik/Shutterstock.com 5% of population 5% of population 50th percentile (average) 95th percentile 5th percentile Figure B Goodheart-Willcox Publisher