November 9, 2011

Usability & UX: forgotten in obesity web intervention?

A group of researchers in the Netherlands just published the results of their web-based adolescent obesity intervention. This kind of intervention is promising because it scales well: more users on a website are essentially free, while adding people to an intervention that requires doctor visits would be much more expensive.

Scaling is important because reaching a significant portion of the large number of obese people (e.g. 1/3 of US adults) will be cost-prohibitive with an intervention that is expensive to scale.

But scaling well only matters if the intervention is effective. Unfortunately for the Netherlands intervention, after two years there was no positive effect on the physical activity, diet, or BMI of the children who participated.

Where’s the usability testing?

Why wasn’t the intervention effective? The authors offer some possible explanations, such as its short duration (“8 sessions of 15 minutes each within 10 weeks”). However, there was no mention of any usability testing, and poor usability could torpedo a web-based intervention just as easily as any other website.

Tools for improving intervention websites

There are a number of tools used especially by web startups that could be beneficial to web-based interventions for obesity and other diseases.

User experience really matters

Users form first impressions of a website in only 50 milliseconds, and this first impression matters:

The lasting effect of first impressions is known to psychologists as the ‘halo effect’: if you can snare people with an attractive design, they are more likely to overlook other minor faults with the site, and may rate its actual content (such as this article, for example) more favourably.

Especially with self-directed web-based interventions, the intervention’s website is directly competing with the other media available to the participant, i.e. everything else on the internet. It’s not surprising that dropout rates are high for web-based interventions.

It seems that good design and usability are necessary, though certainly not sufficient, for long-term success with web-based chronic disease interventions. I’m going to be on the lookout for studies that include rigorous usability testing.

Citation for the Netherlands study:

Ezendam, N. P. M., Brug, J., & Oenema, A. (2011). Evaluation of the Web-Based Computer-Tailored FATaintPHAT Intervention to Promote Energy Balance Among Adolescents: Results From a School Cluster Randomized Trial Archives of pediatrics & adolescent medicine. doi:10.1001/archpediatrics.2011.204


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