PSYC217 Chapter 4 - Research Design Intro Variables - A research idea can be broken down into a set of variables. - Variable: any event, situation, behaviour, or individual characteristic that can differ in some way (e.g., differ in size, degree, nature). " Variables vary (e.g., between people) > things that can have more than one value. · E.g., a researcher interested in the effects of sleep on memory is interested in two variables: sleep and memory. o Both the amount of sleep that people get and how good their memory is varying between individuals. Some people get sleep, and some people have better or worse memory. · Other examples of psychological variables include heart rate, intelligence, gender identity, reaction time, attractiveness, happiness, stress, sexual orientation, age, and personality traits. > each of these variables will have at least two specific levels or values (and in many cases, many more than two). · For some variables, values will have true numeric or quantitative, properties and meaning > the numbers mean something tangible. · For other variables, the values may not be numeric, but instead simply identify different categories. o Example: nationality, the country in which people were born. o Values are different, but do not differ in amount or quantity. Two Basic Research Designs - Researchers must select a study design that will help them answer questions about variables. - There are two general approaches to studying the relationships among variables: 1. Non-experimental methods · Measuring variables to determine whether they are related to one another; also called the correlational method. · With a non-experimental method, relationships are studied by measuring or observing the variables of interest, e.g., ask people to describe their behaviour, directly observing behaviour, recording physiological responses, or examining publicly available information (e.g., census data, participation on public websites). · Once data on both variables are collected, the researcher uses statistics to determine whether there is a relationship between them. 2. Experimental method. " A method that tries to determine if variables are causally related, by manipulating one variable (the independent variable), controlling all other variables, and then measuring the effect on some outcome (the dependent variable). · Experimental method involves direct manipulation of one variable, control of several other variables (those not of interest), and then measurement of an outcome variable (hypothetically affected by the manipulated variable). · The differences between non-experimental and experimental methods have important implications for the types of conclusions we can draw from the results.
Operationally Defining Variables - Once a researcher decides on a method to study the variables of interest, abstract variables must be translated into concrete and specific forms, for either observation or manipulation. " Variables like "aggression" or "amount of reward" must all be defined in terms of the specific method that will be used to measure or manipulate it. - Scientists call this the operational definition of a variable, or operationalization · Operational Definition: definition of a variable that specifies the operation used to measure or manipulate