Measurem Step 1: Defining the
Explanation Step 2: Designing the model Step 3: Checking Assumptions
ent: objectives
Test whether non metric IV's
lead to different levels for a 1. Are the observations independent? The
set of metric outcome treatment variable should only refer to 1 level
variables. The dependent 1.Sample size: at least 20 of treatment variable. If not > use repeated
variable is metric. - observations per cell. measures ANOVA.
2. Are all variances equal across treatment
1 way ANOVA = more than 2 2.Treatments and interactions: variables?
population, 1 factor(IV), 1 decide how many variables - check for homoscedasticity using Levene's
Test whether non
DV. and interactions. Test. If this assumption is rejected > I. if the
metric IV's lead to
sample size is equall accross all treatment
different levels for a set
- N way ANOVA = more than 3. Use of covariates: problems, there is no problem if not >
Anova of metric outcome
2 population, more than 1 covariates act like control Transform the DV into logarithm and test
variables. The
factor, 1 DV. variables and help to identify again, if still not > adjust the cut off for
dependent variable is
and measure the effect of the significance.
metric.
- MANOVA = more than 2 treatment variables. 3. Is the dependent variable normally
population, more than 1 Covariates should be: distrubuted?
factor, more than 1 DV. continous, pre-measured, - Check for normality using Kolmogrov Smirnov
independent of treatment, or Shapiro-Wilk test. If not > if the sample is
ANOVA overcomes the limited number. large, this is not a problem. If not > transform
multiple testing problem the DV to make the distribution more
which is the chances of a symmetric. Sample size cutoff point is 30.
type 1 error.
, Step 4: Estimation the model OR Derive Step 6: Validating
Step 5: Interpretating the results
the factors/clusters the results
1. Impact of interaction: when 2 variables are combined.
Does the impact of a change in one trearment variable
depend on the level of the other treatment variable. Type
of interaction:
- Ordinal: the magnitude of one IV depends on the other,
but direction also depends on the other IV.
- Disordinal: Also the direction depends on the other IV.
Estimating the model
2. Significance of main effects:
Anova calculations:
- disordinal interaction, it does not make sense to check
Xg = group average.
main effects.
X = overall average. Consider
- no interaction or ordinal, it is.
SSBg = sum squared between groups = validation tests
3. Impact of covariates > not interesting.
ng(Xg-X)^2 through control
4. Effect size: partial ETA squared = % of variance
MMSB = mean SSB =. 1/G-1 *G*SSBg variables
explained by IV. R2 check the full variance while ETA
MSSW=mean sum of squares within group. Replicate study
checks per variable.
F value = MSSB/MSSW. Asses whether
5. Direction and signifcance of specific population
variation between group is larger than the
differences.
variation within groups.
- Checking for the mean, if mean is higher means there is
higher effect. 2 approaches to check where the effect
comes from:
- Planned comparison: compare the differences and check
the P value. Several tests needed.
-Post hoc: compares everything to everything. Prevents
multiple testing problem.
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 romeehoeks. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.05. You're not tied to anything after your purchase.