Semester 1 Flashcards
A variable manipulated by a researcher is known as?
An independent variable
A variable that measures the effect that manipulating another variable has is known as?
Dependent variable
Variance is?
An estimate of average variability (spread) of a set of data
A confounding variable is?
A variable that affects the outcome being measured as well as, or instead of, the dependent variable
Six people walk in a room. There are 6 chairs. How many degrees of freedom in chair choice are there in this situation?
5
The mean is?
The sum of all scores divided by the number of scores, the value from which scores deviate least, and a hypothetical value that doesn’t have to be a value in the data set
What does a z-score indicate?
A z-score indicates the number of standard deviations a score is from the mean
What is partial eta squared a measure of?
Effect size
For a normal distributed set of data…
The distribution is symmetrical about the mean, the values for the mean, mode and median are the same, there are scores both above and below 2 standard deviations, approximately 68% of scores fall within +/-1 standard deviations
Bars being highest on the left hand side is said to be…
Positively skewed
A frequency distribution in which there are too many scores at the extremes of the distribution are said to be?
Platykurtic
What is the standard error a measure of?
The variability of sample estimates of a parameter
What is the relationship between sample size and the standard error of the mean?
The standard error decreases as the sample size increases
What is true about the 95% confidence interval of the mean?
95/100 confidence intervals will contain the population mean
What does probability show?
P is the probability of observing a test statistic at least as big as the one we have if there were no effect in the population (I.e the null hypothesis were true)
A type I error occurs when?
We conclude that there is an effect in the population when in fact there is not (false positive)
A type II error occurs when?
We conclude that there is not an effect in the population when in fact there is (false negative)
What does a bonferroni correction do?
Corrects for family wise error
How many independent and dependent variables are there in a one-way repeated measures ANOVA?
Only 1 independent variable and only 1 dependent variable
How many dependent variables must you have for an ANOVA to be conducted?
Only one at interval or higher
How many levels must there be in one independent variable for an ANOVA to be used?
3 or more levels
What do unplanned comparisons do?
Test every possibility and compare each condition to each other
Mauchly’s test does what?
Indicates whether there is a significant difference between the variance of the conditions in a repeated measures ANOVA
What do tests of significance such as ANOVA’s look at?
The probability that the samples are from the same population
What is the cut off point for small effect size (partial eta squared)
0.01
What is the cut off point for medium effect size?
0.06
What is the cut off point for large effect size?
0.14
When looking at degrees of freedom, what 2 columns do you look at?
Corrected model and error
What does it mean it the levenes test is non-significant?
The assumption of homogeneity of variance has not been violated - significant = significant problem
If we are being alpha level of .05 we judge a test to be significant is the p value is?
Less than .05
If you carry out a Krystal-Wallis test and your results are significant what post-hoc test would you run?
Mann-Whitney test
If you carry out a Friendman’s test and your results are significant what post-hoc test would you run?
Wilcoxon test
You have 4 groups and each group drinks one of four different caffeine drinks. How many post-hoc pair wise companions will you need to make?
6
With your 6 post-hocs, what will the new alpha level be?
0.05/6 =0.00833
What is the effect size for a Wilcoxon test?
A statistic divided by the square root of the number of observations
You carry out a study to see the effect of 3 different types of energy drink on runners’ performance. You stage a race and give each runner one of the 3 drinks. At the end of the race, for each runner, you record which drink the runner frank and the position they finished in. Which test would be suitable to use on your results?
One-way independent ANOVA
What is the non-parametric alternative to the one-way between-subjects ANOVA?
Kruskal-Wallis test
What is the Kruskal-Wallis test used to compare?
More than 2 independent groups
What test would you use for repeated measures instead of one-way ANOVA?
Friedmans test
In the Kruskal-Wallis test, the test statistic is based on what?
Ranks of groups
In Friedman’s test, the test statistic is based on what?
Sum of ranks
What is the primary use of a two-way repeated measures ANOVA
To assess the impact of 2 independent variables on a single dependent variable with repeated measures
In a two-way repeated measures ANOVA, what does the interaction effect test?
Whether the effect of one independent variable on the dependent variable depends on the level of the other independent variable
What is a key assumption of a two-way repeated measures ANOVA?
There must be sphericity for both independent variables
If a significant interaction effect is found in a two-way ANOVA, what is a suitable next step?
Conduct post hoc tests to explore the interaction further
In a two-way repeated measures ANOVA, what would a significant main effect for one of the independent variables indicate?
That the dependent variable is significantly different across the levels of that independent variable, regardless of the other independent variable
What is the purpose of the bonferroni correction in statistical hypothesis testing?
It adjusts the significance threshold to control the overall probability of making type I errors when performing multiple tests
What is the key difference between planned comparisons and post hoc tests after finding a significant interaction in a two-way ANOVA?
Planned comparisons focus on specific hypotheses set before the study, while post hoc tests explore all possible comparisons after the data has been analysed
When would it be appropriate to use post hoc tests rather than planned comparisons following a significant interaction in a two-way ANOVA?
When you have no specific hypotheses in mind and want to explore all possible pairwise comparisons
In a psychological study examining the effects of different modalities of therapy, and treatment duration on anxiety reduction, each participant undergoes both types of therapy and is assessed at both time points. Which statistical test would be most appropriate to analyse the data?
Two-way repeated measures ANOVA
After an ANOVA you need more analysis to find out which groups differ. When you did not generate specific hypothesis before the experiment, what should you use?
Post-hoc tests
When the between-groups variance is a lot larger than the within-groups variance, the F-value is… and the likelihood of such a result occurring because the sampling error is …?
Large; low
What is the overall effect of an independent variable on a dependent variable known as?
Main effect
The results of a two-way repeated measures ANOVA with three levels on each independent variable revealed a significant value for Maichly’s test of p=.048. What does this mean?
The assumption of sphericity has been violated
When you have data that violates the assumption of sphericity what should you do?
Use a greenhouse-geisser or huynh-feldt correction
What is statistical power in hypothesis testing?
The probability of correctly rejecting the null hypothesis when it is false
What generally increases statistical power?
Increasing the sample size
What does a priori power analysis help researchers determine?
The size of the sample needed to detect an effect
What is the relationship between effect size and statistical power?
Generally, as effect size increases, statistical power increases
What is a core principle of open science?
Sharing data, materials and methods publicly
What platform is commonly used for open science to share research data and materials?
Open science framework (OSF)
What does the replication crisis refer to in psychology research?
The inability to reproduce the results of published studies
What is meant by reproducibility in the context of scientific research?
Repeating a study using the same data and methods
What is one reason for the replication crisis in psychology?
Publication bias towards positive findings