Predicting Size Breakdown – Trial and Error

One of the unexpected challenges we have met with the emergency wheelchairs is predicting which wheelchair sizes would be needed in an emergency. The destination of the wheelchairs will be unknown when stock is ordered, and the general build of any population varies vastly.

The emergency wheelchairs are manufactured in four sizes, and for our initial stock the size breakdown was based on Motivation’s worldwide database of wheelchairs used by our partner organisations. The wheelchairs were ordered in these proportions:

25% Small

35% Medium

25% Large

15% X Large

However, when the wheelchairs were deployed in the Philippines, the extra-large wheelchairs were not a good fit with the Philippine population who tend to be a smaller build. This resulted in not all of the extra-large wheelchairs being well matched to the wheelchair users that needed them.

A wheelchair that is too large for the wheelchair user can cause immediate mobility difficulties as the user’s arms are not in a good pushing position, but also can cause long term complications such as scoliosis due to the wheelchair user not being well supported.

This will inevitably be an issue where a finite number of products are available, given the need for predicting the sizes when ordering without knowing where they will be used. However we are trying to mitigate this by developing guidelines for what to do with wheelchairs that cannot be well matched (e.g. extra-large wheelchairs are good for hospital transport chairs). We have also decided to alter the stock size breakdown to fit a smaller population in recognition that many natural disasters happen in Asia where populations are a smaller build. Our new proportions for stock will be:

25% Small

45% Medium

25% Large

5% Extra-large

Hopefully, second time round, we’ll have a closer match rate of product size to person