Chapter 10- Introduction to simple experiments Flashcards
(19 cards)
What is the name of the group of participants under the influence of the independent variable.
The treatment group
What is meant by a confound?
An alternative explanation for a result, potential threats to internal validity
What is a design confound?
An experimenter’s mistake in designing the independent variable.
What is systematic variability
When all the members of one group are of a certain variance and the the group are under another (more friendly waitresses in one group than the other.) If it varies across both groups then it is unsystematic variance and does not affect internal validity.
What is selection effects?
When the kinds of participants in one level of the independent variable are systematically different from those in the other as a result of selection methods.
What is meant by matched groups
When researchers want to make it as fair as possible they can rank the participants according to a certain variable and then place them in pairs (1st ranked with 2nd ranked etc) and then randomly assign each pair to different groups.
What is meant by an independent group design?
When different groups of participants are placed into different levels of the independent variable
Distinguish between post test only and pretest/posttest design
In both participants are randomly assigned into at least two groups of two levels of the independent variable (longhand notes/Laptop.) However in postest only the dependent variable is only measured after while in pretest/postest design the variable is also measured before as a control.
What is a repeated-measures design? What type of design is this?
It is a within groups design in which participants are measured on a dependent variable more than once, after exposure to each level of the independent variable.
Name and describe another within groups design
In concurrent-measures design participants are exposed to all levels of of an independent variable at roughly the same time, and a single attitudinal or behavioural preference is the dependent variable (babies looking at faces.)
What are the advantages of within group designs?
Ensures that all participants in the two groups will be equivalent and gives researchers more power to notice differences between conditions. It also generally requires less participants.
What particular threat to validity to within group designs face?
Order effects; when being exposed to one condition may change the reaction to the following condition.
Name and describe two variations of order effects
Practice effects occur when a participant may become better at the activity in the experiment through practice in previous trials or become bored or tired of the experiment. Carryover effects may occur when some form of contamination carries over from one condition to the next. (eating oranges- brushing teeth.)
How can order effects be avoided?
Through counterbalancing (switch the order for half the participants.)
What are the two variations of counterbalancing? Distinguish them and explain when they are used.
Full counterbalancing is usually used when there are 2-3 levels of the variable. Every order of the variables is explored. When there are more levels, partial counterbalancing is usually employed, where only some of the possible condition are represented.
Describe two methods of partial counterbalancing
This can be done by presenting the conditions in a random order for each participant or through the use of a latin square, a formal condition where each sequence appears at least once.
Name the three main disadvantages of within groups designs
1) repeated-measures designs have the possibility of order effects
2) They are often not possible or impractical
3) People can see all levels of the variable and modify their behaviour accordingly (bowl size example)
What is a demand characteristic
A cue that can lead participants to guess an experimenters hypothesis.
Is a pretest/postest a repeated-measures design?
No as they are not exposed to each level of the independent variable.
