PSYC 355 Lecture Notes - Dependent And Independent Variables, Inter-Rater Reliability, Quantitative Psychology
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25 Nov 2012
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Chapter 2: The Scientific Method in Psychology
•Goal of quantitative/ psychology is the explanation of behaviour
•Need language that is precise enough to be understood by others and
general enough to apply it to a variety of situations – this language takes the
form of explanations which are general statements about events that cause
phenomena to occur
•Scientific method – agreed-upon approach to discovery and explanation
oSet of rules that dictate general procedures a scientist must follow in
research
oRules are based on logic and common sense
•Three types of scientific research:
•Naturalistic observations – observation of behaviour of people or animals in
their natural environment
oLeast formal and constrained by fewest rules
oProvide foundation of biological and social sciences
•Correlational studies – examination of relations between 2+ measurements
of behaviour or other characteristics of people or animals
oInvolve more formal measurements of environmental events, of
individuals’ physical and social characteristics, and of their behaviour
•Experiments – study which researcher changes value of an independent
variable and observes whether this manipulation effects value of dependent
variable
oOnly research which can confirm existence of cause-and-effect
relations among variables
Five steps summarizing the rules of scientific method:
1. Identify the problem and formulate hypothetical cause-and-effect relations
among variables
Involves identifying variables (behaviours and environmental and
physiological events) and describing relations among them in general
terms
2. Design the experiment
experiments involve manipulation of independent variables and
observation of dependent variables
each variable must be operationally defined and independent variable
must be controlled so that it is only thing responsible for changes to
dependent variable
3. Perform experiment
organize material, train people to perform it, recruit volunteers,
randomly assign volunteers to experimental group of control group
4. Evaluate hypothesis by examining data from study
Involves special mathematical procedures used to determine whether
observed effect is statistically significant
5. Communicate results
Article, conferences, conventions
•Replication – repetition of an experiment or observational study to see
whether previous results will be obtains; uncovers statistical anomalies
and incompetently conducted research
•Great scientific research occurs as result of long-term research programs
in which findings are part of collective endeavour
•Psychological research in Canada is supported by:
Natural Sciences and Engineering Research Council
Social Sciences and Humanities Research Council
Canadian Institutes of Health Research (Medical Research Council)
Step 1: Identifying the Problem
•Hypotheses - statement, usually designed to be tested by an experiment,
that tentatively expresses a cause-and-effect relationship between 2+
events
•Theory – set of statements designed to explain a set of phenomena,
proposes relationships among variables, and makes new predictions;
more encompassing than a hypothesis
way of organizing system of related hypotheses to explain some larger
aspect of nature
generates testable hypotheses - ones that can be supported or proved
wrong by scientific research
•framework for most psychological research is larger in scope than
hypothesis but smaller in scope than full-fledged theory
Naturalistic Observations
•Naturalistics – people who carefully observe animals in their own
environment, disturbing them as little as possible; observer remains in
background
Step 2: Designing an Experiment
•Variables – anything capable of assuming any of several values (very in
value)
•Manipulate – setting values of an independent variable in an experiment
to see whether value of another variable is affected
•Experimental Group – group of participants in an experiment, members
of which are exposed to particular value of independent variable, which
has been manipulated by researcher
•Control Group – comparison group used in experiment, members of
which are exposed to naturally occurring or zero value of independent
variable
•Variable – anything capable of assuming any of several values
•Independent variable – variable that is manipulated in experiment as
means of determining cause-and-effect