Task 8 Flashcards
How do you manipulate an I.v?
You set its values to at least two different values or “levels”
What are the two ways you can manipulate a variable?
Quantitatively : changing amount if variable to which each group is exposed (29mg,39mg 3etc)
Qualitatively:. Giving participants in different groups different treatments (Prozac,lexapro,zoloft)
What are the three basic types of experimental designs?
Between subjects design
Within subjects design
Single-subject design
What does the between subject design consist?
Different groups of subjects are randomly assigned to the levels of your I.v(data is averaged and analayzed)
What does the within subjects consist of?
A single group of subjects is exposed to all levels of your I.v (databis averaged and analyzed)
What does singles subject design consist of?
Subjects are exposed to all levels of the i.v(like within group design) but you do not average data across subjects instead you focus in changes of Behaviour of a single subject (or small number of individuals) under the different treatment conditions.
What is error variance
Variability amongst scores caused by variables other than your I.v (extraneous variables or subject related variables such as age gender etc)
What are some sources of error variance?
—Subjects differ in innumerable ways
—Environmentak conditions aren’t absolutely constant
-Same subject varies from moment to moment
How can you handle error variance?
Reducing error variance
Increasing the effectiveness of your I.v
Randomizing error variance across groups
Statistical analysis
How to reduce error variance?
—>Holding extraneous variables as constant as possible by treating subjects within a group as similarly as possible (eliminate outside distractions , read instructions same way , follow same procedures)
How do you increase the effectiveness of your I.v?
—> selecting correct levels of your I.v for the experiment (if it’s too low it might not show an impact on the D.v)
How do you randomize error variance across groups?
Randomly assigning subjects to treatment conditions
Resulting in error variance distributed evenly across the groups (canceling itself)
How do you use statistical analysis to reduce error variance?for what?
-Estimating the probability with which error variance alone would produce differences between groups at least as large as those actually observed
—inferential statistics is used
— results are statistically significant when probability is low enough
What are between subject designs ?
Randomly assigning subjects to groups then exposing each groups to a single level of the i.v
What are the types of designs in between subjects design?
The single factor randomized groups design
Matched group design
What other two subtypes of designs can be found in the single factor randomized group design?
Randomized two group design
Randomized multi group design
What is the randomized two group design?
Randomly assigning subjects to TWO groups to different levels of the i.v and taking steos to hold extraneous variable
What are the advanatages of two group design?
—Simple to carry out
—require few subjects
—no pretesting or categorization of subjects
—statistical analysis is simple
What are some disadvantages of the two group design?
—you don’t learn much about the nature of the relationship, or function , relating the i and d variables
—almost no sensititivity to the effect of the i.v (if participants differ greatly, difficult to see effect of i.v)
What does randomized multi group design consist of?
More than two groups
What is a parametric design?
Manipulating the I.v quantitatively
What is a non parametric design?
Manipulating the I.v qualitatively (categorical)
What is a multiple control group design?
When just one control group is not adequate to rule out alternative explanations of results you use a variation on the single factor multi group design is used one that includes multiple control groups
What are matched groups design?
Matched sets of subjects are distributed at random, one per group into the groups of the experiment
