Week 2: Experimental Research

1. Read the following hypotheses and identify the independent and dependent variables in each hypothesis.
   1. There is no difference in users’ reading speed and retention rate when they view the news on a smart phone or on their laptop.
   2. There is no difference in target selection speed and error rate between joystick, touch screen and gestural interface.
   3. There is no difference in the analytical reasoning skills of the children who used Khan Academy videos to learn as compared to the ones who used a book.
2. Imagine you have been tasked to evaluate a brand new smart walking stick for visually impaired users. As a result, you design an experiment and recruit 35 visually impaired users within the city of Rotterdam. Each participant will have to use the new smart stick and the conventional walking stick.
   1. Describe what kind of experiment is this (true, quasi, or non-experiment), and what can you say about the design of the study (between-group, within-group or split-plot)?
   2. Describe how you can prevent or mitigate sources of random and systematic errors in your study design?
3. Read the following situations that may happen during an experiment and comment if they are sources or random errors, systematic errors, or both.
   1. You only recruit males to participate in your experiment.
   2. The sensors that you are using to measure participants’ stress levels are not accurate.
   3. Your participants are often disturbed by loud voices from outside the room.
   4. In a writing task designed to assess participants’ writing speed, participants occasionally make spelling mistakes.
4. Design a quasi-experiment to validate/invalidate the following Null Hypothesis. Please choose the most appropriate design (between-, within-group or split-plot; factorial vs. non-factorial design) for your study and explain the rationale behind your choices.
   • “There is no difference in reading speed and retention rate when users read a news on smart phones, laptops, and newspapers.”