chapter 6 Flashcards
parametric tests
operate on data from a probability distribution, such as the normal distribution or the t-distribution
applicable to ratio data and interval data
non-parametric test
are “distribution free,” which is to say, they make no assumption about the distribution of the underlying data.
the data used in are
nominal categories
you’ll lose information
ANOVA
determines if an independent variable—the test conditions—had a significant
impact on a dependent variable—the measured responses.
tests the data to determine the likelihood of the null hypothesis being true
(tenable) or false (rejected)
F-statistic
used to compare statistical models that have been fitted to a data set to identify the model that best fits the population from which the data were sampled.
p-value
the probability of obtaining
the observed data if the null hypothesis is true.
reporting f-statistics
Placed in parentheses
l Uppercase for F
l Lowercase for p
l Italics for F and p
l Space on both sides of the equal sign
l Space after the comma
l Space on both sides of the less than sign
l Degrees of freedom are subscript, plain, smaller font8
l Three or four significant figures for the F statistic
l No zero before the decimal point for the p statistic (because it is constrained
between 0 and 1)
degrees of freedom
If n is the number of test conditions and m is the number of participants, then the degrees of freedom are (n − 1) for the variance due to Method and (n − 1)(m − 1) for the variance due to Method × Subject.
two-way design
An experiment with two independent variables
chi-square test
procedure for investigating relationships, often used on categorical/nominal data
which non parametric test?: 2 conditions, between-subjects
mann-whitney U
which non parametric test?: 3 conditions, between-subjects
kruskal-wallis
which non parametric test?: 2 conditions, within-subjects
wilcoxon signed rank
which non parametric test?: 3 conditions, within-subjects
Friedman
difference parametric and non-parametric tests
Parametric tests, such as the analysis of variance, assume the data are sampled from a
probability distribution, such as the normal distribution. Provided this assumption is met (and a few others are), parametric tests have more statistical power and are more accurate and more precise than non-parametric tests
What to do if assumptions for parametric test are not met?
(1) proceed with the parametric test,
(2) transform or clean the data in some manner to correct the violations and then proceed with the parametric test,
(3) use a non-parametric test.