Introduction to Statistics Flashcards
Difference between Sample and Target Population?
1) Sample: People we collect info on
2) Target: Larger population
Three types of Bias?
Stats R super!
Sampling: More/less likely to include individuals
Recall: People can’t remember things
Social-Desirability: Incorrect info as societal pressure
Term for if measurement error in data?
Information Bias
What is a Confounding Factor?
Background factor which relates to the outcome and exposure
Difference between Experimental and Observational Study?
Experimental: Researcher changed something (RCT and Crossover Trial)
Observational: Researcher hasn’t intervened (E.g. Case-control, cross-sectional, cohort and ecological studies)
Difference between Retrospective and Prospective Study?
Retro: Look into past (C-Control study)
Pros: Collect info at start and follow over time (Cohort)
Example of a population level study?
Ecological
What happens in a Case-Control study? (2)
1) Find individuals with outcome and take random sample
2) Look to see who did and didn’t have exposure
(Good for investigating a rare outcome)
Case-Control Weakness?
Only investigate single disease, lots of chance of bias
What happens in a C-S Study?
1) Look at what currently is happening (snapshot of time)
2) See who currently has exposure and outcome
What happens in a Cohort study?
1) Collect info on a sample
2) Follow over time to see who gets outcome
What happens in an RTC?
1) Have multiple groups (arms)
2) Give different exposures to each arm and then compare difference
Disadvantages of RTC?
1) Expensive and not good for long term
2) Not always suitable (ethically)
What should a good study include?
- Randomisation of participants to interventions (reduces bias/confounding).
- Show causation rather than association.
- Have outcome measures (results) for at least 80% of the population.
