oneway anova Flashcards
What are independent variables?
variables that are explicitly manipulated
What are dependent variables?
Variables that are our data (ie. FA, HR)
What is the population?
All the data we can observe
What is Random Sampling?
A subset of the population, hopefully representative of the population as a whole
What is Standard Deviation?
A measure of variance
How do you calculate the variance?
SD^2
What is a Normal Distribution (aka Gaussian Distribution)?
The sum of all variables. Has a mean which falls at the highest peak. The variance determines how spread out a distribution is.
What is bimodality?
A distribution that has 2 peaks
What does within-groups mean?
Chance variation
What does between groups mean?
Chance variation and another effect
What is a One-way ANOVA?
A comparison of variation within-groups to variation between groups. Tells us if there is a significant difference among groups but not where that difference is. Produces an F-statistic which produces a p-value.
What does a large F-Stat tell us?
There is evidence that the difference is reliable
What are the Degrees of Freedom for a One way ANOVA?
2
What is an F-Distribution?
Allows us to find the probability of observing an F-Stat with a specific value. The F-Statistic is assessed against the F-Distribution
Why do we need Post Hoc Tests?
- the t-test is probably not enough
- require multiple comparisons
What is the Bonferroni test?
It automatically adjusts the p-value to correct for the number of comparisons. Creates a more conservative false alarm rate.
What is Apophenia?
The experience of seeing meaningful patterns in random or meaningless data
Because of the central limit theorem, many of the variables that we study in psychology are normally distributed. What best describes the normal distribution?
A distribution which has its mode at some value and decreases as you move away from that value in both directions
Which 2 parameters describe the normal distribution?
Mean & Variance
What does the p-value tell us in a one-way ANOVA?
The p-value tells us the probability of observing our sample of data given that the null hypothesis of no difference between groups is true
If there is a systematic effect of our manipulation on the observed data then:
- The between groups variation will be larger than the within-groups variation
- The F-ratio will be sufficiently large
- The means of our conditions will be different
What is one reason why you might conduct post-hoc analyses after running an ANOVA?
The ANOVA tells that there is an effect but not where the effect is (ie. between which groups) or the size of the effect
