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SOAN 2120 Study Guide - Midterm Guide: Time Series, Latin Square, Blind Experiment


Department
Sociology and Anthropology
Course Code
SOAN 2120
Professor
David Walters
Study Guide
Midterm

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SOAN 2120 Textbook Notes
Midterm 2
Chapter 7
Experimental Research
Common sense experiments are when you modify something in a situation and then
compare the outcome to what existed without the modification (ex: car is not working so
you clean the battery and then try again)
Researchers do three things in experiments. First they begin with a hypothesis, then the
modify something in a situation, and finally, they compare the outcomes of the
experiment with and without the modifications in place.
Experimental research is the strongest type of research when testing casual relationships
due to the fact that the conditions that are best suited for causality (temporal order,
association and no alternative explanations) are best when they are done in experimental
research designs
As the sample size increases, individual differences decline in experimental research
Research Questions appropriate for an experiment
Which technique (surveys, experiments) best fit your research question?
By judging your question critically, you can decide which experimental technique is
best suited
Research Questions for experimental research
Research questions that are most appropriate for your experiment should fit your
experiments strengths and weaknesses
Experiment questions should be made so that they can be manipulated to different
conditions (ex: do people who complete a university education increase their annual
income more than people who do not?) we can actually use research questions to find this
out you can’t just randomly assign thousands of people to go to university and
thousands of people to not and then test the results
The experiment is typically best suited for micro level questions with a narrow scope or
scale
Experiments can rarely address questions that require looking at conditions across an
entire society or across decades
Experiments encourage researchers to isolate and target the impact that arises from one or
a few casual variables
Random Assignment
Random assignment is a method for assigning cases (individuals, organizations) to
groups for the purpose of making comparisons
Random selection refers to how sample members (study participants) are selected from
the population for inclusion in the study. Random assignment is an aspect of
experimental design in which study participants are assigned to the treatment or control
group using a random procedure.
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Random assignment is a way to divide or sort a collection of individuals into two or more
groups to increase confidence that the groups do not differ in any way
Random means that an individual has an exactly equal chance of ending up in one of the
other group
Random assignment is unbiased because the researchers desire to confirm his or her
hypothesis or a researcher’s subjects personal interest do not enter into the selection
process
In random sampling, the researcher selects a smaller group from the initial group of
individuals ideally the researcher will have a random sample, and randomly assign
Study of the sophomore- a term used to refer to the potentially limited external validity of
studies based on undergraduate samples, usually using the experimental method (first
year phycology students need to be involved in research studies- but does the data
actually apply to the wider population?)
How to randomly assign
A researcher will divide up individuals into two or more groups by asking them to toss a
coin, throw a dice, count off etc.
Matching versus random assignment
Sometimes researchers will match people based on their gender, or age but it is not
typical
True matching becomes an impossible task
Just because all subjects are male for example, does not mean they are equal in their
characteristics, backgrounds, etc.
Experimental Design Logic
In experimental research, the people being researched are called the subjects
Research experiments are divided into 7 parts, but not all experiments include all 7 parts
The 7 parts include treatment/independent variable, dependent variable, pretest, post-test,
experimental group, control group, random assignment
1) Treatment
The independent variable in experimental research is called the treatment
Independent variables are the variables that the experimenter changes to test their
dependent variable.
The treatment is labelled as an X
EX: A scientist is testing the effect of light and dark on the behavior of moths by
turning a light on and off. The independent variable is the amount of light and the
moth's reaction is the dependent variable.
Researchers want the treatment to have an impact and produce specific reactions,
feelings or behaviors
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2) Dependent Variables
Dependent variables are the outcomes and physical conditions, social behaviors,
attitudes, feelings or beliefs that subjects change in response to the treatment
The dependent variable is labelled as an O
Dependent variables can be measured by observations, interviews, or
psychological responses and reactions (ex: heart rate or sweating palms)
3) Pretest
The pretest is the measurement of the dependent variable before the treatment is
introduced
4) Post-test
The posttest measures the dependent variable after the treatment is introduced
5) Experimental Group
The experimental group is the group that receives the treatment
6) Control Group
The control group is the group that does NOT receive the treatment
Control in Experiments
A researcher should control all aspects of the experimental situation to isolate
the effects of the treatment and to eliminate alternative explanations.
Experimental researchers often use deception to control the experimental setting
Deceptions occurs when the experimenter lies to the subjects about the true
nature of an experiment or creates a false impression through his or her actions
or the setting
Deception allows the researcher to control the subject’s definition of the
situation and prevents them from altering their behavior
Types of Design
EX: a researcher wants to know about whether waiters and waitresses receive more tips if
they introduce themselves by first name and return to ask, “is everything fine” eight to
ten minutes after delivering the food.
The dependent variable is the size of the tip received
The independent variable is the wait staff introducing herself, and returning to asking if
everything is fine
The study occurred in two identical restaurants on different sides of a town that have the
same types of customers and on average the same amount in tips
Classical Experimental Design
All experiments are variations of the classical experimental design which includes random
assignment, a control group, an experimental group a pretest and a post test for each group.
Ex: the experimenter gives 40 newly hired waitresses identical 2-hour training sessions and
instructs them to not introduce themselves or go back to ask how the meal was. The
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