Rest of lectures

Question 1

Mixed models

Answer 1

models that incorporate both fixed effects (parameters that are constant across individuals or groups like age, sex, meassured concentration) and random effects (parameters that vary across individuals or groups; the variable that intorduces dependancy into the data like patient meassured before and after treatment, patient is the random effect (same person=depedancy) and if measured twice like different patient then results are different).

They are used to analyze data that have a hierarchical or nested structure, allowing researchers to account for variability at multiple levels and to make inferences about the population.

mixed models are used when you get clustering within your data (the awnsers will likley be more alike as they come from a similar group, like asking 2 siblings (same houshold) or same person same question 6 month later (not much changed) -> grouping related data points.
If you dont take account of clustering p value will be biased

Question 2

Difference pseudoreplication and dependancy

Answer 2

Pseudoreplication is a statistical mistake that arises from treating dependent observations as independent, while dependency is a characteristic of the data that mixed models specifically address