Web-browsers are basically used to interpret HTML. If other technologies are used like JavaScript, Java applets, or audio/video players, the installation of plugins is necessary. Most Web-browsers have them pre-installed but this does not guarantee its proper functionality. So using these technologies in web-based studies can produce technical dropout because of the technical burden to install the plugin or the unwillingness to invest this extra time.

In a large restricted online study on two different samples (UNET: students of the University of Vienna, n=1,369; WISO-Panel: people from all walks of life, n=764) we analysed if using a Java applet produces a technical dropout and if this leads to a distortion of demographics.

The dropout on the Java applet questionnaire page was 10.5 times higher than the mean dropout on the remaining six pages without any additional technologies (2.3% vs. 24.1%). We found no difference for participants’ age in the somewhat homogeneous UNET student sample but a significant difference in the WISO-Panel (t[762]=2.7, p = .012). Participants who dropped out on the Java applet questionnaire page were 2.6 years older. In both samples a sex-specific effect on technical dropout appeared (UNET: OR=1.34; 95%-CI [1.05, 1.69]; WISO-Panel: OR=1.42, 95%-CI [1.00, 2.02]). Women more frequently dropped out on the Java applet questionnaire page.

Although many technologies are already pre-installed in many web-browsers and are commonly used, using additional technologies can still be dangerous in producing a biased younger and male dominated sample.