Basic Experimental Design
This week we will begin basic experimental design. We will address:
- Overall research strategy What is being studied, why, who are our participants...
- Internal Validity; how well we understand what led to results within the experiment.
- External Validity; how well our results generalize outside the the experiment.
- “Ecological” Validity; how much particular characteristics of the researcher, the participants, the research setting, and the larger culture influence our results.
- Basic Experimental Designs; core components of true research designs
- Control groups
- Experimental treatments
- General experimental controls
Lecture notes are here.
What will be on the exam Wednesday?Exam material is primarily from the lectures; use the PowerPoint lecture notes I provide each week to study for it. During each lecture I announce specific topics that will show up on the exam. Use the PowerPoint notes and my descriptions of what will show up on the exam during lectures to study. To encourage students to attend lecture (and ask questions!) I have provided study guides at the end of each lecture. Examples of exam items are posted here.
Testing the Hypothesis, A conceptual Introduction and Sharing the Results.
Click the image for a reading on interpreting negative results in research.
Is Pluto a planet?
How much is the way we categorize the natural world a matter or politics, convenience, or sentiment, versus externally valid, "hard" science? Many astronomers and planetary scientists – much less the Disney Corp. – have a sentimental attachment to Pluto as our distant planetary underdog. However, who actually decides whether something is a planet, and on what grounds?
Pluto is in the Kuiper Belt, a region of ice and rock past Neptune. As we have learned more about that region since Pluto was first discovered it is clear that if Pluto is a planet, then dozens of other icy/rocky objects in the Kuiper Belt may also be eventually considered planets, using the criteria that they have enough gravity to be round, and orbit the sun. The planets wouldn't seem as special if there were 50 or 60 of them. Perhaps we could exclude all the other balls of rock and ice in the Kuiper zone, and just let in Pluto on sentimental grounds. Does it matter (other than to Pluto lovers)? Click the image for an interesting discussion from New York Times.
Discussion group AssignmentDiscussion sections meet in computer labs, TBN.
Begin your paper: develop your topic and theory, learn how to do computer searches.
Your TA will teach you how to conduct a computer search to flesh out your topic and write your paper. To facilitate that we will meet in computer labs. Your TA will give examples of searching for articles, then you will form dyads and work through your own paper ideas.
Look at the paper assignment to see what your term paper will consist of. For this week you will decide on a research question, find a theory that addresses it, and develop a hypothesis. Your TA will discuss the paper week, and will help you search for relevant journal articles. To get comfortable reading journal articles go to Guide to Psychology Articles.
Type a paragraph or two on each of the following. (Your assignment is a typed page or so, but we strongly encourage you to write more to get a start on your paper and get feedback from your TA.)
1. Phenomenon: What is the larger question? What are you interested in explaining?
Think of a general behavioral question, in the form of one Hypothetical Construct relating to another, e.g., “…what creates vulnerability to drug use…” or "how does using computers affect learning...?" The question may be as topical as these, or may be more basic, such as "what brain structures are active during language learning...?" You may also think of a more applied question, such as "What is the most effective way to prevent drug use among youth...?"
2. Theory: How does it work? What causes what? Why or how does it happen?
Describe a psychological theory that helps you understand the “why” or “how” part of the question. So, you may theorize that "…people are tempted to use drugs when they see attractive other people using them…” This simple “how it works” statement points you toward published studies (i.e., on peer pressure...) and, eventually, to a hypothesis. Your Introductory text is a good place to find descriptions of general psychological theories.
3. Hypothesis: What is your specific prediction?
Turn your general question and theory into a hypothesis: make a prediction about specific variables that can be operationally defined, and that reflect the hypothetical constructs underlying your theory. Look in your Week 1 lecture notes for each of these terms:
- it can specify a manipulation (for an experiment) or a measurements only;
- The variables must be concrete enough that you can describe specific operations that you will use to create or measure each variable
- It must clearly express the larger hypothetical constructs you are studying.
We will return to these questions for your assignment in Week 8, where you will begin a first draft of your term paper.