Experimental Research and Design Flashcards
What is ‘Experimental Research’?
Manipulation of an independent variable. An attempt is made to hold all other variables except the dependent variable constant - ‘Experimental Control’.
Effect is observed of the manipulation of the independent variable on the dependent variable - observation.
Uses the deductive method
it can produce important knowledge about cause and effect.
Rarely is conducted in a controlled setting or environment
it relies primarily on the collection of numerical data.
What is ‘Experimental Control’?
Attempts to predict events that will occur in the experimental setting by neutralising the effects of other factors;
Physical Control
Selective Control
Statistical Control
What is ‘Physical Control’?
Gives all subjects equal exposure to the independent variable.
Controls non experimental variables that affect the dependent variable.
What is ‘Selective Control’?
Manipulate indirectly by selecting in or out variables that cannot be controlled.
What is ‘Statistical Control’?
Variables not conducive to physical or selective manipulation may be controlled by statistical techniques (example: covariance).
What is ‘Experimental Design’?
A blueprint of the procedure that enables the researcher to test his hypothesis by reaching valid conclusions about relationships between independent and dependent variables.
It refers to the conceptual framework within which the experiment is conducted.
What is ‘Internal Validity’?
Asks did the experimental treatment make the difference in this specific instance rather than other ‘Extraneous Variables’?
What is ‘Extraneous Variable’?
‘Extraneous Variables’ are undesirable variables that influence the relationship between the variables that an experimenter is examining.
Another way to think of this, is that these are variables the influence the outcome of an experiment, though they are not the variables that are actually of interest.
These variables are undesirable because they add error to an experiment. A major goal in research design is to decrease or control the influence of extraneous variables as much as possible.
Example of ‘Extraneous Variable’
Say you wanted to work out how clever a fish species were in finding food depending on how long since they had eaten. But if their ability to find food also depended on the temperature of the water and you were not able to either control or measure accurately the temperature of the water. Then the temperature could be described as an ‘Extraneous Variable’.
Factors effecting ‘Internal Validity’?
History Maturation Pre-Testing Measuring Instruments Statistical Regression Differential Selection Experimental Mortality Interaction of Factors
History
Maturation
Measuring Instruments
Statistical Regression
Differential Selection
Interaction of Factors
What is ‘External Validity’?
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Asks to what populations, settings, treatment variables, and measurement variables can this observed effect be ‘Generalised’?
What is ‘Generalisability’?
Generalisability theory, or G Theory, is a statistical framework for conceptualising, investigating, and designing reliable observations. It is used to determine the reliability (i.e., reproducibility) of measurements under specific conditions.
Factors effecting ‘External Validity’ or ‘Generalisability’?
Pre-Testing
Differential Selection
Experimental Procedures
Multiple Treatment Interference
Tools of ‘Experimental Design’ Used to Control Factors Jeopardising ‘Validity’?
Pre-Testing
Control Group
Randomisation
Additional Groups
What is a ‘Pre-Test’?
A ‘Pre-test’, or measurement before the experiment begins, can aid control for differential selection by determining the presence or knowledge of the experimental variable before the experiment begins. It can aid control of ‘Experimental Mortality’ because the subjects can be removed from the entire comparison by removing their ‘Pre-tests’.
However, pre-tests cause problems by their effect on the second measurement and by causing generalizability problems to a population not pre-tested and those with no experimental arrangements.
Example of ‘Pre-Test’?
Example: Subjects take a Pretest and think about some of the items. On the Post-test they change to answers they feel are more acceptable. Experimental group learns from the pretest.
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What is ‘Experimental Mortality’?
The loss of subjects from comparison groups could greatly affect the comparisons because of unique characteristics of those subjects.
Groups to be compared need to be the same after as before the experiment.
Example of ‘Experimental Mortality’?
Over a 6 month experiment aimed to change accounting practices, 12 accountants drop out of the experimental group and none drop out of the control group. Not only is there differential loss in the two groups, but the 12 dropouts may be very different from those who remained in the experimental group.
What is a ‘Control Group’?
The use of a matched or similar group which is not exposed to the experimental variable can help reduce the effect of History, Maturation, Instrumentation, and Interaction of Factors. The control group is exposed to all conditions of the experiment except the ‘Experimental Variable’.
What is ‘Randomisation’?
Use of random selection procedures for subjects can aid in control of ‘Statistical Regression’, ‘Differential Selection’, and the ‘Interaction of Factors’. It greatly increases ‘Generalisability’ by helping make the groups representative of the populations.
What are ‘Additional Groups’?
The effects of ‘Pre-tests’ and ‘Experimental Procedures’ can be partially controlled through the use of groups which were not pre-tested or exposed to experimental arrangements. They would have to be used in conjunction with other pre-tested groups or other factors jeopardising ‘Validity’ would be present.
Regression Towards the Mean?
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Ecological Validity?
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Assignment Errors?
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