Research Strategies: How Psychologists Ask and Answer Questions
Module 3
Research Strategies: How Psychologists Ask and Answer Questions
Description
Correlation
Research Strategies: How Psychologists Ask and Answer Questions
Experimentation
Statistical Reasoning
Description
Case Study
Case Study
A clinical study is a form of case study where the therapist investigates the problems associated with a client.
Survey
A technique for ascertaining the self-reported attitudes, opinions or behaviors of people usually by questioning a representative, random sample of people.
Survey
Wording can change the results of a survey.
Q: Should cigarette ads and pornography be allowed on television? (not allowed vs. forbid)
Survey
A tendency to overestimate the extent to which others share our beliefs and behaviors.
Survey
From a population, if each member has an equal chance of inclusion into a sample, we call that a random sample (unbiased). If the survey sample is biased, its results are spurious.
Naturalistic Observation
Observing and recording behavior of animals in the wild, to recording self-seating patterns in lunch rooms in a multiracial school constitute
naturalistic observation.
Descriptive Methods
Correlation
Correlation Coefficient is a statistical measure of relationship between two variables.
Scatterplots
Scatterplots
Data
Scatterplot
Correlation and Causation
Illusory Correlation
The perception of a relationship where none exists. Parents conceive children after adoption.
Order in Random Events
Given random data we look for order, for meaningful patterns.
Order in Random Events
Given large number of random outcomes, a few are likely to express order.
Experimentation
Like other sciences, experimentation forms the backbone of research in psychology. Experiments isolate causes and their effects.
Exploring Cause & Effect
Many factors influence our behavior. Experiments (1) manipulate factors that interest us while keeping other factors under (2) control.
Effects generated by manipulated factors isolate cause and effect relationships.
Independent Variable
Independent Variable is a factor, manipulated by the experimenter, and whose effect is being studied.
For example, to study the effect of breast feeding on intelligence. Breast feeding is the independent variable.
Dependent Variable
Dependent Variable is a factor that may change in response to independent variable. In psychology it is usually a behavior or a mental process.
For example, in our study on the effect of breast feeding on intelligence. Intelligence is the dependent variable.
Evaluating Therapies
In evaluating drug therapies it is important to keep the patients and experimenters assistants blind to which patients got real treatment and which placebo.
Evaluating Therapies
Assigning participants to experimental (Breast-fed) and control (formula-fed) conditions by random assignment minimizes pre-existing differences between the two groups.
Experimentation
Comparison
Statistical Reasoning
Describing Data
Measures of Central Tendency
Mode: The most frequently occurring score in a distribution.
Mean: The arithmetic average of scores in a distribution obtained by adding the scores and then dividing by their number.
Median: The middle score in a rank-ordered distribution.
Measures of Central Tendency
A Skewed Distribution
Measures of Variation
Range: The difference between the highest and lowest scores in a distribution.
Standard Deviation: A computed measure of how much scores vary around the mean.
Standard Deviation
Making Inferences
A statistical statement of how likely an obtained result occurred by experimental manipulation or by chance.
Making Inferences
Making Inferences
When sample averages are reliable and the difference between them is relatively large, we say the difference has statistical significance.
For psychologists this difference is measured through alpha level set at 5 percent.