XP-2-Experiments

cause-and-effect relationship

The goal of the experimental research strategy is to establish the existence of a - between two variables

Manipulate; isolate

To accomplish this goal, an experiment must - one of the two variables and - the two variables being examined from the influence of other variables

true experiment

to rule out the possibility of a coincidental relationship, an experiment, often called a -, must demonstrate the changes in one variable are directly responsible for causing changes in the second variable

1. Manipulation

2. Measurement

3. Comparison

4. Control

Four basic elements of an experiment

Manipulation

by changing a variables’s value to create a set of two or more treatment conditions

Measurement

A second variable is - for a group of participants to obtain a set of scores in each treatment condition

Comparison

scores in one treatment condition are - with the scores of another treatment condition

Control

all other variables are - to be sure that they do not influence the two variables being examined

Independent variable

variable being manipulated

Dependent variable

variable being measured

Extraneous variable

other variables that may affect the findings

Third variable problem

although a study may establish two variables are related, it does not necessarily mean that there is a direct (causal) relationship between the two variables

Third variable problem

As weight increases from child to child, mathematical ability also tends to increase. However, this does not mean that an increase in weight causes an increase in mathematics ability

Manipulation and control

elements unique in an experiment

Manipulation

consists of identifying the specific values of the independent variables to be examined and then creating a set of treatment conditions corresponding to the set of identified values

Manipulation

allows the researcher to determine the directionality of the problem

Control

a researcher must ensure that the observed relationship is not contaminated by the influence of other variables

1. Holding a variable constant

2. Matching

3. Randomization

three standard methods for controlling extraneous variables

Holding a variable constant

by standardizing the environment and procedures

Holding a variable constant

All individuals in the experiment could be observed in the same room, at the same time of the day, by the same researcher

Matching

A researcher using two samples of college students could assign 20 younger students (under age 25) and 10 older students (25 or older) to each separate treatment condition

Counterbalancing

change the order of manipulation from one participant to another

Randomization

use of a random process to help avoid a systematic relationship between two variables

Randomization

the goal is to disrupt any systematic relation between extraneous variables and the independent variable, thereby preventing the extraneous variables from becoming confounding variables

Random assignment

the use of a random process to assign participants to treatment conditions

Holding constant and matching

the two methods require some extra effort or extra measurement

external validity

Holding a variable constant has limited generalization or -

Comparison

An experiment always involves -

Experimental condition

condition in which the treatment is administered

Control condition

condition in which the treatment is not administered

No-treatment control condition

condition in which the participants do not receive the treatment being evaluated

No-treatment control condition

they provide a standard of normal behavior or a baseline

Placebo

inert or innocuous medication, a fake medical treatment such as a sugar pill or water injection that, by itself, has absolutely no medicinal effect but produces a positive or helpful effect simply because an individual expects or believes it will happen

Placebo effect

occurs simply because the individual thinks the medication is effective

Nocebo effect

happens with an inert substance that produces a negative or harmful effect simply because an individual expects or believes it will happen

Manipulation check

additional measure to assess how the participants perceived and interpreted the manipulation and/or to assess the difect effect of the manipulation

Simulation

is the creation of conditions within an experiment that stimulate or closely duplicate the natural environment in which behaviors being examined would naturally occur

Stanford Prison Experiment

The intent of the research was to study the development of interpersonal dynamics and relationships between guards and inmates in a prison

Field study

research conducted in a place that the participant or subject perceives as a natural environment