Review of the Wearables in Practice Symposium – April 6th 2018

An exciting and informative Symposium!

Friday 6th of April, finally we were heading to Soesterberg with a nice group from the University Medical Center Groningen (UMCG) to visit the “Wearables in Practice” symposium, which was organised by the Human Factors department of TNO (the Dutch Organisation for Applied Natural Scientific Research). The theme of the Symposium, Wearables in Practice, covered many of the new, smart, devices we increasingly see on the market. From smartwatch to accelerometer, and even smart alcohol meters which could help addicts, all facets of smart, wearable devices were represented here.

The day itself was organised very well, with an interesting program, and it was a lot of fun to take a look at what is happening at TNO. Also the diverse backgrounds of guests, from bussinesses to universities, and even the Royal Dutch Airforce, made it an interesting, diverse, and especially informative day. As cherry on top, I was invited to give a presentation about ACTman, a new piece of software developed by me in cooperation with scientists from the UMCG and the University of Groningen. ACTman finally allows researchers to automatically process and analyse physical activity data within mere seconds! This is especially impressive given the far longer times it took prevously to process and analyse such data, and that it cuts out a lot of the manual labour involved. As such, ACTman facillitates researchers and people interested in physical activity data in analysing large amount of activity data quickly and accurately.


Buyers Guide: Actigraphs

Points to consider

One of the most common questions I get from fellow scholars is: "Which Actigraph is most suitable for my study?".

However, it is hard to give a simple and straightforward answer, as the optimal choice for your situation depends on your study design, e.g.,  study duration, sample characteristics, analysis goals, et cetera.

As such I have compiled some points which should be considered when choosing an actigraph for academic purposes:

1. Does the considered actigraph provide you with the raw data?

This is one of the most important points when considering actigraphs for academic purposes, and one of the most overlooked ones. 

"Why is this so important?", you might ask. Well, when the raw data is not provided, the data can be somewhat akin to a black box. That is, you will have no idea what happened to the data beforehand. Perhaps the manufacturer uses a transformation on the data, or perhaps some smoothing functions. This will often be documented very sparsely, if at all.

As such, you will have at best only a partial idea of what your data respresents, possibly obfuscating your results, and your control over your own study.

Hence, when a device offers you access to the raw data you will have a better idea what happened to it and what it really means.

2. In what kind of unit will the actigraph measure?

This point is very much related to the first one. There are various units in which the actigraph can deliver its data. For example gravity units, activity 'counts', and manufacturer-specific units.


3. How long will the considered actigraph last before it needs new batteries?

This is an important point as battery issues can seriously hamper the quality of your dataset. Even worse, the maximum battery duration given by the manufacturer might well be an overstatement which fails to materialise under normal conditions.

In the case of one of our own studies we were once confronted with an actigraph which boasted a battery life of 4 months. As such, we designed our whole study around this period. Hence our dismay when participants returned en masse with their empty actigraphs after a mere 2 months.

Thus, we had to make an ad hoc change to our design wherein we sent participants a new actigraph near the 2 months mark. This lead to unexpected costs for sending devices, an extra burden for participants, and worst of all missing data.

Therefore, make sure you know and test the actual battery life when considering an actigraph for your study!

4. User comfort and material safety


My Garage: Peugeot 205 GTi

Garage: Peugeot 205 GTi

Can't forget my old love,

a raw, free-revving 1.6, in a light and nimble chassis,
really rewarding to drive hard. Pushed my limits time and time again in this baby.

Hope to drive one of these angels again..
My old Peugeot 205 1.6 GTi:

Identifying the Parts of an Alfa Romeo GTV

Parts Katalog: Alfa Romeo GTV (916; Spider)

Knowing exactly which part of your Alfa you might be working on, can save you a great deal of work . 

When working on my GTV, I frequently consult this Parts Katalog [1]. It offers plentiful visual aids in identifying the individual parts, and gives rough price estimates.

Example page

This Parts Katalog can be found on, which offers a wide range of downloadable workshop and car documentation.

[1] GTV-Spider_(916) Katalog. (n.d.). Retrieved from