week 8 Flashcards
(31 cards)
What is a population in statistics?
All possible subjects or data points of interest, such as all users, devices, or behaviors in an HCI study.
What is a sample in statistics?
A subset of the population selected for measurement and analysis, ideally representative and randomly chosen.
What are independent variables in a study?
Variables that the researcher manipulates intentionally to examine their effect on dependent variables.
What are dependent variables in a study?
Variables that are measured to observe the impact of changes in independent variables.
What is the purpose of hypothesis testing?
To determine whether observed effects in a study are likely due to random chance or a real underlying effect.
What is a null hypothesis (H₀)?
A statement that there is no effect or difference; any observed outcome is due to chance.
What does p < 0.05 mean?
There is less than a 5% probability that the observed data would occur if the null hypothesis were true—typically considered statistically significant.
What is a Type I error?
Rejecting the null hypothesis when it is actually true (false positive).
How do you reduce Type I errors?
By lowering the alpha level (e.g., from 0.05 to 0.01) or using Bonferroni correction for multiple comparisons.
What is a Type II error?
Failing to reject the null hypothesis when it is actually false (false negative).
How can you reduce Type II errors?
By increasing the sample size or the statistical power of the test.
What is a t-test used for?
To compare the means of two groups to see if the difference is statistically significant.
What is the difference between one-tailed and two-tailed t-tests?
One-tailed tests look for a difference in one direction; two-tailed tests check for any difference, regardless of direction.
When do you use an independent t-test?
When comparing two separate groups (between-subject design).
When do you use a paired t-test?
When comparing the same group under two conditions (within-subject design).
What is an ANOVA used for?
To compare means across more than two groups or to evaluate multiple independent variables simultaneously.
What is a main effect in ANOVA?
An overall effect of one independent variable on the dependent variable, ignoring other variables.
What is an interaction effect in ANOVA?
Occurs when the effect of one independent variable depends on the level of another variable.
What does η² (eta squared) represent?
It is a measure of effect size in ANOVA: 0.01 = small, 0.06 = medium, 0.14 = large effect.
What is counterbalancing in experimental design?
A technique used to minimize order effects by varying the sequence of conditions across participants.
What does GLMM stand for?
Generalized Linear Mixed Model
What types of variables does a GLMM include?
Fixed factors and random factors
What are fixed factors in a GLMM?
Independent variables with set levels
What are random factors in a GLMM?
Variables where levels are random samples from a larger population
