Health effects can often be small or hard to measure. Longitudinal studies have been an important tool and area of study for researchers within the health domain for a long time. These studies can last anywhere from some months, to decades and provide important information to society and breakthroughs to science. A common methodology is the use of Experience Sampling Method or ESM, which asks participants to regularly fill in surveys within the longitudinal study. For this, we have developed our very own TIIM app, which can be controlled and used from an everyday smartphone.