Concept of Exclusion

In HFE, the term “exclusion” refers to the percentage of the population that a particular design does not accommodate. 

In the example of a small door, the door might exclude tall people if it is not tall enough to accommodate their height.

For example, if the height of the door is designed to accommodate the 95th percentile of the population, it means that it is suitable for use by 95% of the population. However, this also means that 5% of the population, or the remaining 5th percentile that are unusually tall, may not be able to use the door comfortably or at all. 

The concept of exclusion is important in the field of design because it helps designers to understand the limitations of their designs and to consider the needs of a diverse range of users. By understanding the dimensions and proportions of the human body, designers can create products and environments that are accessible and usable by the greatest number of people possible.

However, it is important to note that it is not always possible or practical to design for the entire population. There may be trade-offs involved, such as cost or aesthetics, that limit the extent to which a design can accommodate a wide range of body sizes and proportions. In these cases, designers may need to consider the needs of the most common or most important users and make decisions about which groups to prioritize. This is generally also where the importance of adjustability arises. We will return to this later.