Factorial Designs Flashcards
What is a factor?
an independent (predictor) variable
What is a 2x2 factorial design table?
a 2x2 table showing the 4 possible treatment combinations
eg Active drug, treatment 1 Active drug, treatment 2 Placebo, treatment 1 Placebo, treatment 2
When are 3x3 factorial design table used?
to trail the doses of drugs when used in combination
what are levels of a study?
refers to the potential options for a factor that can be applied to a individual study unit
Where can factorial design be used in study design
Randomisation
Recruitment
Randomised controlled feasibility trial
DDELPHI (Doctor DELivered PHysical activity intervention)
Why perform a factorial design study?
allows multiple factors to be investigated & allows for comparison between levels of the same factor
What are the 3 potential scenarios of drug and therapy interaction?
No interaction (parallel lines)
Interaction effect between the two (non parallel lines)
different Interaction between groups dependant on age
What is a split plot design?
eg a field divided into 4 plots eg plot gets a different species and then each plot is divided into 4 and a different pesticide is used per section
can be used in hospitals for clinical trails
How can trail contamination take place?
accidental application of care due to auto pilot
participants may seek help elsewhere
participants in treatment group share knowledge with control group
public health intervention
how can trail contamination be combatted?
using cluster randomisation (all patients in same ward receive same intervention)
what is a Latin square design?
square grid eg 3x3 with letters and numbers C1,C2,C3 R1,R2,R3
each representing a level with the factor
When is Latin square design used?
when the all factors have the same number of levels or for diagnostic comparison study
rarely used because of rules
Why should statistical problems be thought about when designing experiment
so problems aren’t encountered later on
eg experimental or observational sample size sampling methods which tests
what is nominal data?
categories are named
what is ordinal data?
categories are named and ordered
