Exam (elaborations)
Psychology 2812 - Statistics for Psychology II - Final Exam
- Course
- Institution
Psychology 2812 - Statistics for Psychology II - Final Exam
[Show more]
Content preview
Psychology 2812 - Statistics for Psychology II - Final Exam1.Week 6!: One Way ANOVA and the GLM.
2.Characterize a t test.: - 2 groups.
- Used to compare means of two independent samples (groups).
3.What are H0 and H1 in an ANOVA/the omnibus f test?
Additionally, what is the p value?: - H0:
- Groups sampled from populations with the same mean.
- H1:
- Groups not sampled from populations with the same mean.
- P-value:
- What is the probability of observing differences between groups as
large as the ones observed, if H0 is true?
4.What is an ANOVA?: A statistical test that compares the means of two
or more groups.
5.Characterize a one-way between-subjects ANOVA.: - Has only one
indepen- dent variable.
- Since it is between subjects, each participant contributes an
observation in only one group.
6.ANOVA computes an "omnibus" (overall) F-statistic, which is a ratio of
two variances.
The numerator is the variance, the denominator is the
variance.: between groups variance; within groups variance.
Conceptually, this is the ratio of treatment to error variance,
7.What is the rationale behind ANOVA?: If the variance between
experimental conditions is markedly greater than the variance within
the conditions, it suggests the independent variable is causing the
difference.
8.Omnibus F-statistic is a metric of the "overall" question...: "Are the
means of the groups the same? (or not the same)?"
9.What does an f ratio far above 1.0 mean?
Relatedly, what does an f ratio far below 1.0 mean?: - F-ratio far above 1.0:
- Between groups variance is larger than within-groups variance.
,- F-ratio below 1.0:
- Between groups variance is smaller than within groups variance.
10.Under the null hypothesis we expect the F-statistic to be close to 1.0
most of the time.
But due to random sampling, under the null hypothesis, sometimes it will be
.: larger.
11.In ANOVA, an omnibus F statistic can take on values:
- A. Between -1.0 and 1.0.
- B. Between 0.0 and 1.0.
- C. Between 0.0 and infinity.
- D. Between -infinity and infinity.: - C. Between 0.0 and infinity.
- The F-statistic in an ANOVA is always positive!! It can not be negative!!
12.In what case do we not perform a follow up test after running an
omnibus f test?: If the f test is not significant!
13.What are SSb and SSw?
What is the equation for each one?: - SSb:
- Sum of squares between.
- Each group mean minus the grand mean of all the groups.
- SSw:
- Sum of squares within.
- Each observation minus the group mean to which it belongs.
14.The ANOVA omnibus f test examines whether the differences
between group means are real or due to random chance.
What does Gribble mean by "real" in this case?: By "real", he means faithfu
representation of the differences between the means of the underlying
population(s) from which each sample was drawn.
15.What is the equation for the omnibus f test? What does it tell us?:
- MSbetween ÷ Mswithin.
- Gives an overall measure of the difference between all group
means together, relative to the variability within each group.
16.What are the assumptions of ANOVA?: - 1. Normality of the residuals.
- 2. Homogeneity of variance across groups.
- 3. Independence of observations.
,17.True or false?
If the normality assumption is violated, we can not use ANOVA.: False!
If the normality assumption is violated, we can still use ANOVA, but we
should use a non-parametric test!
18. When
normality is violated for ANOVA, we use the test that
works on ranks of data and not the data itself.: Kruskal Wallis.
19.What test do we use for homogeneity of variance?: Levene's test!
20.True or false?
If the homogeneity of variance assumption is violated, we can still use
ANOVA, and we would use the Welch one way test instead of the regular
ANOVA f test.: True!
21.What would an example of a clear violation of the independence of
obser- vations assumption be?: Repeated measures within each group.
22.ANOVA is a model of your data just like regression / multiple-
regres- sion.: linear.
23.What are the consequences of estimating for 3 parameters instead of 1?:
- We "pay" by moving 2 degrees of freedom for the MSw term to the
MSb term.
- This makes it harder to reject the null hypothesis/find a statistically
significant difference.
- We need to make sure the increase in SSb is worth it!
- It's a tradeoff.
24.Week 9!: One Way ANOVA: Follow Up Tests & Statistical Power.
25.Statistical significance tells you how likely it is that a result is due to
chance rather than a real effect, and it is given be the .: p
value.
26.Define effect size.: Effect size gives us a measure of the size of the
difference between groups.
An effect is a primary measurement that you use to test your hypothesis
and the effect size is the magnitude of that effect.
27.What is eta squared (·2)?What is the equation?: - A statistic used
ANOVA to measure the proportion of variance in a dependent variable
explained by an independent variable.
, - ·2 =SSb ÷ SStot.
- Ranges between 0 and 1, just like R2 in regression.
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 HESIGRADER001. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $22.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75057 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now