At the center of the infographic is a graphic of a mobile phone with two messages on the screen. The message at the top reads, Research question: Does texting while driving cause accidents? The second message reads, To test the research question, you must control participants, variables, and study implementation. Three balloons lead from the phone to the three sections of the infographic. At the top, a graphic labeled Variables shows a car following a path among traffic cones. The text to the right follows:
Independent Variable:The variable that researchers deliberately manipulate. Example: The independent variable is texting while driving; experimental group drives through obstacle course while texting; control group drives through obstacle course without texting.
Dependent Variable: The variable measured as an outcome of manipulation of the independent variable. Example: The dependent variable is the number of accidents (objects hit in obstacle course).
Extraneous Variable: An unforeseen factor or characteristic that could interfere with the outcome. Example: Some participants have more driving experience than others. Without controlling the amount of driving experience, we can't be certain the independent variable caused more accidents.
To the left of the phone graphic is a graphic labeled Participants. The graphic shows several rows of small stick figures along with several differently shaded figures identified with arrows. A callout from one of the differently shaded figures leads to the text, which reads as follows:
Representative Sample: Subset of the population chosen to reflect population of interest. Example: Participants must be college students. Other groups might be affected differently by the independent variable.
Random Sample: Method used to ensure participants do not introduce unexpected bias. Example: Researchers recruit participants by randomly selecting students from the college directory.
To the right of the phone graphic is a graphic labeled Study Implementation, showing two stick figures each labeled Question Mark. The text reads as follows:
Random Assignment: Process by which researcher randomly assigns participants to experimental or control group. Example: Experimenter flips coin to determine participant’s group.
Experimenter Bias: Researchers’ expectations and unintentional behaviors can unwittingly change the outcome of a study. Example: Without thinking, researcher says “good luck” to one group. This might unintentionally cause them to try harder. Researchers control for these effects by using a double-blind study in which neither researcher nor participant knows what group participants are assigned to.