independent variables thesis

Layout the design for two between-subjects experiments: a) an experiment involving an experimental group and a control group, and b) a factorial design with three independent variables that have three, and two levels respectively.

Class – this one is tricky. We are more than halfway through the course, so it’s going to start to pick up in rigor. You will need to carefully read all materials to get an understanding of the research design. You need to have IVs and levels on the IV.

A two-group design is defined as having one independent variable with two distinct levels: the experimental group and the control group (Myers & Hansen, 2012).

Experimental designs will allow for random assignment to each group, whereas quasi-experimental designs will have pre-determined groups, such as age or gender. To contrast, factorial designs will typically have more than one independent variable with two or more levels on each factor (Myers & Hansen, 2012).

Let’s say I want to know if stress impacts memory. I have two different ways that I’m going to go about it: The first is with a two-group design where I just want to see how people that report any amount of stress do on a memory test.

In the second experiment, I want to dig a little deeper to see how different amounts of stress, different amounts of sleep, and gender impact memory (measured by performance on a memory test). Here is how I will set up each of my experiments:

Two Group Design

IV: Stress

·      Level 1: Control group = No stress

·      Level 2: Experimental group = Stress

DV: Performance on a Memory Test

Factorial Design (3x2x2) – Remember, the amount of numbers is how many IVs there are. In this case, I will have 3 IVs. Do you see it? The actual numbers indicate how many levels on each IV there are. In this case, I will have 3 levels on the first IV, 2 levels on the second IV, and 2 levels on the third IV. Here is an example:

IV1: Stress

·      Level 1: Low

·      Level 2: Moderate

·      Level 3: High

IV2: Sleep

·      Level 1: 5-6 hours/night

·      Level 2: 7-8 hours/night

IV3: Gender

·      Level 1: Women

·      Level 2: Men

DV: Performance on a Memory Test

As you can see, I’ve created two quasi-experimental designs. Your designs can be quasi-experimental or you can design true experiments. The idea is that you understand how to set up a two-group design, as well as a factorial. Give it a shot!

Reference:

Myers, A., & Hansen, C. H. (2012). Experimental psychology (7th ed.). Belmont, CA: Thomson/Wadsworth. ISBN-13: 9780495602316