Class notes
Lecture notes Advanced Research Methods And Statistics For Psychology: Clinical Psychology
- Course
- Institution
Notes from all three lectures of the ARMS - clinical track.
[Show more]
Seller
Follow
inkikeizer
Content preview
Specific track Clinical Clip 1Power and effect size & Randomization + manipulation check
Effect size (beta) = Objective and standardized measure of the size of an observed effect (proportion
of total variance in the dependent variable that is associated with an independent variable)
- partial eta squared in an ANOVA:
small effect .01, medium effect .06, large effect > of gelijk aan .14
- Pearson r in a regression: size of a correlation
small effect .10, medium effect .30, large effect > of gelijk aan .50
When partial eta squared is larger: more relevant result
Statistical power = possibility of detecting an existing effect of a particular size, therefore the
opportunity to correctly reject the null hypothesis. The power is 1 – beta, where beta is the probability
of a type 2 error.
- Your goal is to get as much data as necessary to have a power of at least 0.80.
If your sample is large and your effect size is small, you can reduce the sample to increase the effect
size.
Type 1 error (alfa) = the probability that an effect will be detected where in fact no effect exists: the
null hypothesis (H0) is rejected when in fact it is true.
Type 2 error (beta) = the probability that no effect will be detected where an effect does in fact
exists: the null hypothesis (H0) is not rejected when in fact it is false -> chance of false negative
- the possibility to detect an effect (the power) depends on the p-value that is chosen (so the chance for
a type 1 error). It also depends on the effect size and the type 2 error.
.
, Experimental research: Objective = establish causal relationships
Only variable A -> causes change in variable B
Three relevant comparisons:
- Comparison 1: Baseline comparison/measurement with the control group to determine whether your
experimental groups differ -> they should not differ
Randomization = you check whether the participants in your study are allocated to a group or
condition at random or whether this was determined by the researcher.
- Comparison 2: Adresses variable A (the factor that you manipulated and not just measure) -> you use
a manipulation test to check whether factor A was manipulated by the researcher: post-manipulation
measurement for all groups/
- Comparison 3: The actual effect you’re looking for (this can be done with the number of
measurements you did) ->
pre-post measurement = compare an outcome before an intervention and after an intervention.
This would be a longitudinal design: strongest design to determine causation. Or you can measure at
one time point (cross-sectional design in which you compare your experimental/intervention group
with a control group)
Randomization check = are the groups equal prior to the manipulation?
- not significant: excellent
- significant: include covariates (explore the influence)
Manipulation check = Was your manipulation of factor A successful?
- significant: excellent
- not significant: you cannot conclude anything about the effect of the manipulation.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller inkikeizer. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.77. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
83822 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now