Percentile Ranges in Anthropometrics
Percentile
A percentile is a value that shows how a data point compares to the rest of the data, dividing the set into 100 equal parts.
Percentile Range
A percentile range represents the proportion of a population whose body dimensions fall at or below a certain value.
- Anthropometric data is typically presented in tables or charts that show a range of body measurements for a specific population.
- Each measurement is listed alongside key percentiles, commonly the 5th, 50th, and 95th.
5th Percentile
- The value below which 5% of the data falls.
- Consideration for smaller individuals.
- A consideration when involving reach and accessibility.
- Door handle height: Allows shorter users and children to open doors independently
- Emergency stop buttons: Positioned so even the shortest user can reach quickly
50th Percentile
- The middle value (median), divides the data into two halves.
- Average individuals.
- Used for general use products with low safety risk.
- Bathtub depth: Designed to allow the average adult to enter and exit comfortably, while providing sufficient water coverage for bathing.
- Kitchen counter height: Based on average standing elbow height for comfortable working
- Designing exclusively for the 50th percentile can exclude a significant portion of the population.
- Always consider the broader range of users.
95th Percentile
- The value below which 95% of the data falls.
- Larger Individuals.
- A consideration when involving sufficient clearance / space.
- Car headroom: Ensures taller users can sit upright comfortably without hitting the roof.
- Hospital beds: Length and width sized to safely accommodate patients at the higher end of height and weight ranges.
Designing for a Range
5th–95th Percentiles
- Providing adjustability or a range of sizes accommodates for a greater range of people
- Increased levels of inclusivity, however, the extremes are still excluded.
- Often used for safety equipment.
- Office chairs: Adjustable seat height and backrest accommodate users with different leg lengths and torso heights.
- Clothing sizes (S–XL): Standard sizing based on the range between 5th and 95th percentile body measurements (e.g. chest, waist, hip)
Designing for extremes (e.g., 5th and 95th percentiles) can increase complexity and cost.
What anthropometric data is most appropriate when determining the minimum doorway height of a public bus to ensure head clearance for most users?
- 5th percentile
- 50th percentile
- 95th percentile
- 5th–95th percentile
Solution
1 mark for the correct answer: c - 95th percentile
This ensures that most users fit, especially those on the taller or larger end of the spectrum
For each of the following design contexts, state the most appropriate percentile that a designer should consider: (5 marks)
- Car dashboard controls – reach
- Doorway height
- Public seating width
- ATM screen height
- Office chair height
Solution
| Design Context | Consideration | Percentile Used | Justification |
|---|---|---|---|
| Car dashboard control - reach | Distance from seat to buttons | 5th | Ensures smaller users can reach all controls safely and comfortably |
| Doorway height | Maximum head clearance | 95th | Prevents taller users from hitting their head when walking through |
| Public seating width | Hip breadth | 95th | Accommodates larger individuals to ensure comfort and accessibility |
| ATM screen height | Eye level when standing | 50th | Provides a central reference point suitable for most users |
| Office chairs height | Popliteal Height | 5th-95th | Ensures chairs are comfortable and adjustable for most users |
- Identify three products and explain which percentiles were likely used in their design.
- Consider how these choices impact usability and inclusivity.
