W5 Flashcards
What can you run instead of doing multiple T tests?
A 1-way independent ANOVA
Good or bad if the homogeneity of variance is greater than 0.05
Good
What does ANOVA ask the question of?
How successful the experimental manipulation has been in comparison to the natural variability that exists
What does ANOVA compare?
Type of variance you want (effect variance) with the type of variance you don’t want (error variance).
When do significant effects occur in the independent ANOVA?
When you have 4 times as much variance between your groups as you do within your groups.
Equation for f-ratio
Variability between treatment conditions / variability within treatment conditions
Effect + error / error
Q. Calculate the population variance of the following numbers:
81, 92, 67, 84, 76
69.20
- Calculate mean
- Subtract mean from each value in data set = deviance.
- Square all deviance values
- Total all deviance values
- Divide total by no of data.
Q. What is the ratio between effect variance and error variance called?
F ratio
Q. True or false? The lack of a significant p value does not enable you to conclude that the intervention had no effect.
True
Q. In an independent ANOVA if the SSwithin value is 312.45 and the dfwithin value is 14. What is the MSwithin value?
22.32
Q. In an independent ANOVA if the SSbetween value is 259.78 and the dfbetween value is 2. What is the MSbetween value?
129.89
In an independent ANOVA you have 3 groups with the following means:
Group 1: 28, 26, 37, 39, 14
Group 2: 31, 22, 32, 28, 19
Group 3: 15, 17, 21, 27, 32
What is the SS value for the means (SSm)?
20.91
Q. What value is calculated to counteract the effect of extreme values on the range of a data set?
IQ range
Q. In an independent ANOVA if the SSbetween value is 198.74 and the SStotal value is 502.47.What is the effect size (ŋp2)?
0.40
Q. True or False? The standard error is smaller than the standard deviation.
True
Q. Your output from a one way independent ANOVA revels a p value of 0.079. Is there a significant difference between the groups?
No
Q. In an independent ANOVA you have 3 groups each with 10 participants. If your SSm value is 22.48, what is your SSbetween value?
224.80
Q. You have an F ratio of 3.98 and your critical value table for your degrees of freedom shows a critical value of 3.89. Are your findings significant?
Yes
Q. What is another term for the deviance squared?
Sum of squared errors
Q. In an independent ANOVA if the SSwithin value is 347.21 and the dfwithin value is 15. What is the MSwithin value?
23.15
Q. In an independent ANOVA you have 3 groups each with 8 participants. If your SSm value is 24.16, what is your SSbetween value?
193.28
Q. True or false? A Bonferroni correction can be used to mathematically account for an increased error rate.
True
Q. What is another word for p value?
Alpha
In an independent ANOVA if the SSbetween value is 398.59 and the dfbetween value is 3. What is the MSbetween value?
132.86
Q. What can we use to determine if our F ratio is significant?
Critical value table
Q. How do we describe a relationship between two variables that obviously are not affected by each other?
Spurious correlation
When calculating the sample variance (If values in a data set are from a random sample drawn from some larger
population) then we divide the numerator by,
n-1
A p value of 0.07 is another way of saying
There is an approximately 7% chance that the observed effect is a chance occurrence
If the null hypothesis is true, the ANOVA F values is expected to be close to
1
If the null hypothesis is false, the ANOVA F value is expected to be
Substantially greater than 1
If the F statistic is greater than the critical value of F, the null hypothesis should be
Rejected
Dividing the Sum of Squares (SS) by the degree of freedom (df) results in what
Mean sum of squares
The MSbetween is divided by MSwithin to produce the
F value
The most common effect size used for an ANOVA is partial eta squared. If a study were to be done in which treatments for the effective of three different diets for weight loss were compared and partial eta squared = .22, which of the following would be the best interpretation of partial eta squared?
The type of diet people received explained 22% of the variability in weight loss
The null hypothesis in ANOVA is that
all the sample means are the same
Post hoc tests are needed whenever you
Reject the null hypothesis and there were more than two IV conditions
When you enter data into SPSS to run an independent one way ANOVA you should have
A column for the independent variable and a column fro the dependent variable
How do you compute the dfbetween
No. of treatment conditions - 1
How do you compute dfwithin?
No. Ppl in study - no. of treatment groups
If tow separate studies have the same dfbetween and the same dfwithin which of the following statements are true?
The Critical value for F is the same for both studies
When treatment conditions vary in their effectiveness (i.e. some treatments are better tha others) the data will tend to have what?
large MSwithin
