week 9 Flashcards
(31 cards)
What is nominal data?
Data that consists of categories without any order, like names of countries or yes/no responses.
What statistical test is used for nominal data in between-subject design?
Chi-square (ꭓ²) test, because it assumes independent observations.
What is an example of nominal data in VR studies?
Participants report ‘Yes’ or ‘No’ to motion sickness after exposure to different VR environments.
What does a significant Chi-square test indicate?
That the independent variable (e.g., type of induction) significantly affects the dependent nominal outcome.
How do you calculate degrees of freedom for Chi-square?
df = (r - 1)(c - 1), where r = number of IV levels, c = number of DV categories.
What is ordinal data?
Data with a meaningful order but not evenly spaced intervals, like satisfaction ratings from 1 to 5.
What test is used for ordinal data in within-subject designs?
Friedman test, a non-parametric alternative to repeated measures ANOVA.
What is an example of using the Friedman test in HCI?
Comparing satisfaction ratings for three reward types (visual, auditory, visual+auditory) in a VR game.
What does a significant Friedman test result mean?
The type of reward mechanism significantly affects satisfaction levels.
What non-parametric test compares ordinal or numeric data between two groups?
Mann–Whitney U test, used instead of an independent t-test.
What is the Wilcoxon Signed-Rank test used for?
To compare two related conditions (within-subjects), as an alternative to the paired t-test.
What does a significant Wilcoxon test suggest?
That there’s a meaningful difference between paired conditions (e.g., before vs after redesign).
What test is used for continuous ratio data in non-parametric analysis?
Permutation test, useful for both between-subject and within-subject designs.
What is the essence of permutation testing?
Assessing whether the observed mean difference is extreme under the null hypothesis by resampling data and counting outcomes.
What is an example of a permutation test?
Comparing task completion time for two mobile UIs by calculating the distribution of mean differences under random label assignments.
What is correlation analysis used for?
To assess the direction and strength of a relationship between two variables.
What does a positive correlation indicate?
As one variable increases, the other also increases. The correlation coefficient is between 0 and 1.
What does a negative correlation indicate?
As one variable increases, the other decreases. The correlation coefficient is between -1 and 0.
What does correlation strength refer to?
How tightly two variables are connected, regardless of direction.
Can correlation be used in both within- and between-subject designs?
Yes, but in within-subject designs, data should be averaged to ensure independence of each point.
What is Pearson correlation?
A parametric test measuring linear relationships; assumes normal distribution and uses continuous ratio data.
What is an example of Pearson correlation in HCI?
Analyzing if faster typists (typing speed) make fewer errors (error rate).
What is Spearman’s rank correlation?
A non-parametric test measuring monotonic relationships; uses ordinal or ranked data without assuming normality.
What is an example of Spearman’s rank correlation?
Evaluating if higher task difficulty is associated with lower user satisfaction ratings.
