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.

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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

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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:

Welcome to my Website and my First Post here

This month I  gave a interview to the Dutch Arts and Auto magazine. This magazine provides information that could interest healthcare professionals around their work and spare time. They also have a website with additional news. Thanks to Monique Bowman and Kees van de Veen for the interview and photo's!

English after Dutch

De ultieme droomauto van psycholoog/aio Yoram Kunkels (31) is een Maserati Quattroporte. Maar aangezien z'n budget twee jaar terug helaas geen dikke ton maar een krappe vierduizend euro bedroeg, rijdt hij in plaats daarvan voorlopig een Alfa Romeo GTV turbo V6 uit 1996. “Dat was de auto met het meeste vermogen voor dit budget. En hij wordt alleen maar meer waard verwacht ik, want het is een echte liefhebbersauto.”

Dat Alfa's geplaagd worden door pech, heeft hij zelf gelukkig nog niet ervaren, vertelt Yoram, die gediplomeerd automonteur is maar zich tegenwoordig (“de autotechniek vond ik niet uitdagend genoeg”) aan het UMC Groningen verdiept in onder meer transities in hartritmes bij depressies. Wat zijn eigen hartslag betreft: die schiet omhoog zodra hij zijn 2.0 V6 turbo met 270 Nm koppel de vrije teugel geeft op de Duitse Autobahn. “Dat is natuurlijk het voordeel van in Groningen wonen. Ik zit met m'n GTV zo in Duitsland.”

The ultimate dreamcar of psychologist/PhD-student Yoram Kunkels (31) is a Maserati Quattroport. But since his budget two years ago unfortunately was not a good 100.000,- but only a tight 4.000,-, he is currently driving an Alfa Romeo GTV turbo V6 from 1996. “That was the car with the most power for this budget. And it will only increase in how much it's worth, because this is a real collector's car.”

That Alfa's tend to be plagued by problems, is something he luckely cannot confirm himself, tells Yoram, who is a qualified car mechanic but who nowadays (“being a car mechanic was not challenging enough”) is investigating transitions in heart rhythms during depression. As far as his own heartbeat is concerned: it shoots up as soon as he releases his 2.0 V6 turbo with 270 Nm of torque on the German Autobahn. "That is of course the advantage of living in Groningen. I'm quickly in Germany with my GTV. "