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03-A: Pseudoscience, Science, or Common Sense?
03-A: Pseudoscience, Science, or Common Sense?
What are some examples of how early psychologists failed to support their assumptions with legitimate research?
What are the core principles of modern psychological science?
WATCH: Phrenology and the Psycograph to see an example of how psychologists failed to support their assumptions with legitimate research.
READ: Psychology as a Science
Read from the top of the page including the sections titled The Key Features of a Science and The Scientific Process, then stop when you reach the Psychological Approaches and Science section.
03-B: Theories and Hypotheses
03-B: Theories and Hypotheses
What is the difference between a theory and a hypothesis?
What is null hypothesis testing?
What does it mean for a result to be statistically significant?
What is the difference between Type I and Type II error?
READ: Science at Multiple Levels
READ: Hypothesis Testing - Read from the beginning, skip the small section on "number of tails" and stop when you reach the Experiment Design section.
03-C: Populations and Samples
03-C: Populations and Samples
What is the difference between a research population and a research sample?
What is the process of random sampling (also known as probability sampling)?
Sampling is the process of selecting a representative group from the population under study.
The target population is the total group of individuals from which the sample might be drawn. The population is the group we want to understand and gain knowledge about.
A sample is the group of people who take part in the research study. The individuals who take part are referred to as participants.
Generalizability refers to the extent to which we can apply the findings of our study to the target population we are interested in.
WATCH: Random Sampling
Note that random sampling is entirely different from random assignment.
03-D: Methods for Collecting Data
03-D: Methods for Collecting Data
How do researchers use each of the following to test their hypotheses? Be prepared to give a few original examples of how you would use each method to collect data.
Measurement methods
Naturalistic observation
Structured observation
Self-report
Psychophysiological
Archival
Measurement timelines
Longitudinal study
Cross-sectional study
Study designs
Case study
Correlational study
Controlled experiment
What are some advantages and disadvantages of each method/design?
03-E: Operationalizing Variables
03-E: Operationalizing Variables
What does it mean to operationalize a conceptual variable? Be prepared to apply this to any psychological concept we may want to measure (e.g., depression, level of attraction to another person, optimism, intelligence, parenting style, aggression) or manipulate (e.g., mood, self-esteem, fatigue, stress level, amount of testosterone in your bloodstream).
READ: Operationalization
03-F: Research Biases & Errors
03-F: Research Biases & Errors
What are some of the most common ways that mistakes in research methodology can introduce errors and biases into the data?
Placebo effect
Rosenthal effect (also referred to as the Pygmalion Effect)
Demand characteristics
Social desirability
How do researchers avoid making these errors?
How is the Clever Hans effect an example of a specific bias? How would you prevent the effect?
VISIT: Research Biases & Errors
03-G: Correlational Designs
03-G: Correlational Designs
What does it mean to say that two variables are correlated?
How would you describe examples of
Positive correlations?
Negative correlations?
Why do we have to be so careful about how we interpret correlations? Be prepared to take an example of a correlation, describe four possible explanations, and discuss why from the correlation alone we cannot be certain which explanation is true.
What is a spurious correlation?
READ: Values of the Pearson Correlation to learn more about the different correlations
READ: Correlation Regression and Linearity for more information on correlation vs. causation
If we took a survey of children’s eating habits and grades in school we would likely find that those who eat a healthy breakfast have higher grades than those who do not. In fact, Cheerios has mentioned research findings in their commercials implying that if you feed your child their cereal, he or she will do better in school. But is that really what the data tells us? With a statistically significant correlation between two things, like (X) nutritional breakfast and (Y) grades, several things are hypothetically possible:
Changes in X cause changes in Y - Eating a better breakfast does, in fact, cause better grades.
Changes in Y cause changes in X - Learning more causes students to eat a better breakfast.
Both of the above are true and the two variables are reciprocally determined... eating better causes academic improvements AND learning more causes better eating habits.
There is something else, like socioeconomic status (S.E.S.), that influences both breakfast consumption and academic performance. Healthy food tends to be more expensive than junk food, and the families that can afford a lot of healthy food can also afford other resources that help students (books, computers, tutors, etc.). Therefore, the two are technically related, but not because one directly affects the other.
Because we can not be sure which of the three it is by just measuring breakfast and grades, all we can say is that there is a correlation between the two -- we can NOT say that eating a good breakfast will cause better grades (no matter how reasonable that claim might seem). A strong correlation is still an important finding, and the predictions that we can make can be useful... we just have to acknowledge the difference between what we can conclude and what we cannot.
When we look at two variables that are mathematically correlated but are not related to each other in a meaningful way we call this a spurious correlation. For example, it is true that there is a positive correlation between ice cream sales and the number of people that drown on a given day. However, does it really make sense that ice cream sales are causing people to drown? Could it be that people drowning is causing others to buy more ice cream? No, the more reasonable explanation is that the relationship is being caused by something else... in this case, temperature. On hotter days more people buy ice cream and more people go swimming. On colder days there is less of each. Thus, the relationship between ice cream sales and drownings is a spurious correlation because one variable is not truly influencing the other. To stress one point: in the case, ice cream sales and drownings are in fact correlated, just because that is a spurious correlation does not change the mathematical relationship between the two... only our understanding of why they are correlated.
Just for fun... Homer demonstrating a spurious correlation
OPTIONAL: If you want to see some more (and pretty amusing) examples of spurious correlations check out http://www.tylervigen.com
The take home message: just because two variables are statistically correlated we cannot assume that we know that changes in one is causing changes in the other. "Correlation does not imply causality."
03-H: What makes a research study a true experiment?
03-H: What makes a research study a true experiment?
How do we differentiate between the independent and dependent variables?
What does it mean to randomly assign participants to experimental conditions?
Why is random assignment essential if we want to conclude that it was our manipulation of the IV that caused differences in the DV?
How are between-subjects and within-subject experiments different? What is getting randomly assigned in each kind of experiment?
Referring back to the article in the previous section, what are some variables that could not (or would not) be manipulated or randomly assigned? How would we study them with a correlational design?
VISIT: Conducting Experiment
03-I: Ethics
03-I: Ethics
What are some general principles for ethical research? For each be able to explain each term and provide an examples of what might constitute a violation.
Voluntary participation
Informed consent
Risk of harm
confidentiality & anonymity
What is an Institutional Review Board (IRB) and how does it help ensure that research participants are treated in an ethical way?
READ: Ethics in Research
Optional: If you are interested in learning more about the American Psychological Association's ethical principles you can find them here: General Ethical Principles
03-J: Replicating Studies
03-J: Replicating Studies
What are the differences between:
Direct (exact) replication
Conceptual replication
What are some of the reasons why some studies in psychology (and other areas of science) are not replicating?
One important part of the scientific method is replicating findings. Sometimes this is called reproducing findings. If a study's finding is correct, it should be able to be replicated. Scientists can replicate studies by doing the exact method again or they can try and reproduce a previous study's finding using different operationalizations. For example, let's imagine that I have a hypothesis that pets cause happiness. I ran a study where I randomly assigned half of my participants to care for a puppy for a week and the other half of my participants did not have a puppy. Then I asked my participants "How happy are you on a scale from 1-10?" In my study, I found that people with puppies were happier.
A direct replication of my study would be another researcher doing the exact same method that I used to test my hypothesis. Another researcher would randomly assign half of their participants to care for a puppy for a week and the other half to not have a puppy. Then they would ask their participants "How happy are you on a scale from 1-10?" Hopefully, they would then find that people with puppies indicated more happiness.
A conceptual replication would be a study that tests the same hypothesis but with different operationalizations. For example, the researchers would have half of their participants keep a rabbit for one week while the other half had no rabbit. Then they would count how many times each participant smiled in the course of one hour. The conceptual variables in the hypothesis, "pets cause happiness" are the same, but the operationalization of those conceptual variables are different.
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