Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

601 > T test > Flashcards

T test Flashcards

(85 cards)

Start Studying
1
Q

What does the T test assess?

A

Differences in the means of 2 data sets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Assumptions of the T test

A
  1. Sample drawn from normal population
  2. randomly selected
  3. homogeneity of variance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why T test instead of Z test?

A

-Z test innacurate with small sample sizes
-T distributions are similar in shape to normal distributions but have thicker walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the student’s T test account for?

A

Bias in the estimate of the SEm (standard error of the mean)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Types of T tests

A
  1. Single Sample
  2. Independent
  3. Dependent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does a single sample T test compare?

A

mean against a known population
(actual mean difference between the sample and the population)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what does an independent t test compare?

A

samples independent from one another

Usually compares two different groups of people

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does a dependent t test compare?

A

Repeated measures

correlated samples (same subject tested twice)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the t -ratio?

A

-Signal to noise ratio
-signal = difference between means (numerator)
-Noise = standard error of the mean difference (denominator)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Important points about the T test

A

T test does not identify the causative factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Purpose of a repteated measures t test

A

If subjects are tested more than once
i.e. pretest posttest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the Size of Effect, why is it relevant?

A

The magnitude of difference

Just because an effect is statistically significant does not necessarily mean that the effect is meaningful.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

SSW

A

Sum of Squares within: how much variation is there within the sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

SSB

A

Difference between group mean and mean of means (between groups)
group mean - grand mean squared for each group.

how much variation there is between the samples

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the F statistic

A

Test value for an ANOVA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the result if F stat is higher than F critical

A

Reject Ho accept Ha

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is alpha level

A

Probability of rejecting null hypothesis when its true (type I error)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the result if p is less than alpha?

A

Reject Ho

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does an ANOVA test?

A

the liklihood that the samples came form the same population

compares the means of two or more groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the F - Ratio?

A

The ratio of the between group and within group variance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why do an ANOVA instead of multipel T tests?

A

Increased risk of type 1 error

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the F value if the null hypothesis is true?

A

F = 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is sheffe’s CI?

A

Most conservative Post Hoc Test
All possible comparisons - combo comparisons (more than just pairwise)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Example of scheffe’s analysis

A

average of several different treatments against control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Symbol for Scheffe's CI?
I
26
what is "k"
number of groups
27
what is Falpha
F critical value from tables
28
HSD
Tukey's Honestly Significant Difference -calculates the minimum raw score mean difference that must be attained to declare statistical significance between any two groups.
29
Difference Between HSD and I
Tukey's does not make all possible comparisons, only makes pairwise
30
n (lowercase)
size of groups *this assumes they are equal
31
q (tukey's)
value from studentized range distribution
32
MSe
Mean square error value from the ANOVA analysis
33
Eta Squared
(h squared) Same as R squared The magnitude of effects of treatment
34
Eta Squared value of .52
52% of the total variance can be explained by the treatment effect
35
RM ANOVA
Repeated Measures ANOVA within subjects design same subjects measured two or more times
36
What is the T test analog of the RM ANOVA?
dependent t test
37
Assumptions of an RM ANOVA
Normality and Homogeneity Sphericity
38
What does sphericity require?
the variance of the difference of all scores are equal
39
What happens if sphericity is violated?
inflate the type I error rate
40
Within Subjects Design
Repeated Measures ANOVA
41
Between Subjects Design
Single Factor ANOVA (one way)
42
Interindividual Variability
Variability between people in different groups
43
Intraindividual Variability
Variability in a persons scores
44
Sources of Variability
1. Interindividual Variability 2. Intraindividual Variability 3. Variability between groups due to treatment effects 4. Variability due to error (inter, intra, unexplained)
45
Variability due to error
unexplained variability
46
Result of eliminating interindividual variability
reduce mean square error in the denominator of the F ratio (like dependent t test)
47
SStotal
total sum of squares
48
SStime
variance due to differences between time periods
49
SSsubjects
Variance due to differences between subjects (t is the number of time periods)
50
F ratio for RM ANOVA
MStime / MSerror
51
Corrections to RM ANOVA
Greenhouse - Geiser (GG) adjustment Huynh -Feldt (HF) adjustment
52
Greenhouse-Geiser Adjustment
WHEN VIOLATION IS SEVERE! Adjustment degrees of freedom for RM ANOVA - estimate of epsilon (sphericity) correction for lack of sphericity *assumes maximum violation
53
Huynh-Feldt Adjustment
WHEN VIOLATION OF SPHERICITY IS LESS SEVERE Adjustment degrees of freedom for RM ANOVA correction for violations of sphericity
54
Sphericity
assumes that the variances of the differences between all combinations of related groups (levels) are equal. In simpler terms, it assumes that the spread or dispersion in one condition is the same in all other conditions.
55
When Can Post Hoc Tests be used in RM ANOVA
Tukey's can be used when sphericity is not violated
56
What can be used in place of post hoc analysis of RM ANOVA if sphericity is violated?
dependent t test with bonferroni correction
57
Factorial ANOVA
Analyize multiple factors on the DV simultaneously (FACTORS AND LEVELS)
58
Main Effects
Individual factor F values
59
Interactions
Combined F values
60
A graph of an ANOVA with no interaction should show lines that are
Always parallel and evenly spaced (same variance)
61
A graph of an ANOVA with an interaction should show lines that
Are not always parallel or evenly spaced (different variance)
62
Types of Factorial ANOVA
- Between- Between - Between- Within (Mixed) - Within – Within
63
What is an ANCOVA
Analysis of Covariance: Adjusts the DV for the covariates allowing you to asses the effect of the IV on the DV while controlling the effects of covariates combo of regression and ANOVA
64
Covariate
A variable that might affect the DV but is not the variable of interest
65
Axis of DV
Y
66
Axis of IV
x
67
When do you use an ANCOVA?
When analyzing the effects of multiple IVs on DV in same model -1 or more interval / ratio IV (performance rating 1-10) -1 or more nominal IV (Time to finish)
68
ANCOVA assumptions
homogeneity of regression - slope between covariate and DV similar
69
If the slopes of a regression are not parallel what does that mean for ANCOVA?
assumption is violated ANCOVA not safe to use
70
Reliability
does the test measure what its supposed to
71
Inter rater reliability
are the outcomes consistent from researcher to reseracher for same subject
72
intrarater reliability
are the outcomes consistent if the same rater administers the test to a given subject
73
Test retest reliability
are test scores fromt eh same subjects similar between multiple occasions of taking the test.
74
ICC
reliability measurement Intraclass Correlation Coefficient: reliability coefficeint true score variance / total variance how consistent ratings are
75
what is required for ICC?
variance terms from RM ANOVA
76
SEM
Standard Error of Measurement reliability measurement measure of the precision of individual test scores
77
Nonparametric Tests
Distribution free generally less powerful do not make assumptions about the distributions of the population used when data does not fit the criteria for parametric tests
78
Examples of nonparametric tests
Mann-Whitney U Test Kruskall-Wallis H test Spearmans' Rank Correlation Coefficient Chi-Square Test of Independence
79
What does a Chi Square Test compare?
two or more sets of NOMINAL data that have been arranged by frequency significant association between two categorical variables
80
Spearman Rho
(p) ORDINAL non parametric equivalent to pearson r
81
Mann-Whiteney U test
quantifies relationship between two sets of ordinal data Non parametric equivalent of indepenent T test
82
Kruskal Wallis ANOVA
Quantifies difference between more than two groups of RANKED data Nonparametric equivalent to the one way ANOVA
83
Friedman's two way ANOVA
Quantifes the difference betwen RANKED data when measured on subjects three or more times Nonparametric equivalent to RM ANOVA
84
IF THE P VALUE IS LESS THAN THE ALPHA LEVEL!!!!
REJECT HO!!!!!
85
Meta Analysis
Procedure that allows an investigator to statistically combine the results of multiple studies

601 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions