Studied by 2 peopleIntroduction and Experimental Design Concepts
What are the types of Variables in data?
Categorical and Quantitive
What is the definition of a Categorical variable
Divides the cases into groups/ categories
What is the definition of a Quantitative variable
measure a numerical quantity for each cases
What is the subcategories for Categorical
Nominal and Ordinal
What are the subcategories of quantitative data?
Discrete and Continuous
Define Census
information collected from whole (finite) population
Define Sample Survey
Information collected from a subset of the \n population
***Often use the approach to sampling (and data collection) to distinguish between options...
Why do we want to use Sample Statistics?
to make inferences back about Population Parameters allowing for RANDOMNESS
How do you describe the population
by measuring relationships between variables at a point-in-time (correlations)
What matters most in samples and why?
RANDOM SELECTION! without it, we get biased
What are the variables when it’s a design for an experiment
Treatment variable and outcome variable
What are the **other** variables when it’s a design for an experiment and define it
EXPLANATORY VARIABLES
attributes we can measure that explain variation in the Outcome
e.g: The Treatment variable is just a ‘special case’ of an \n explanatory variable
CONFOUNDING VARIABLES
attributes we cannot measure that explain variation in the Outcome
e.g: With COVID-19 this might be attitudes to social distancing, approach to hygiene and isolation, or your job situation
What are cons in observational studies (rather than experiments)
Can have SEVERE BIAS due to background effects
Correlations are not Causation
What are observational studies useful for?
guiding the development of hypotheses for later experiments
We look for evidence of a response in a group getting the treatment BEFORE implementing a large expensive double-blind randomised controlled experiment
Observational studies are useful for reinforcing the results of double-blind randomised controlled experiments
Define Single-Blind Trials
the participant does not know if they are \n Treatment or Control
Define Double-Blind Trials
neither the administrator of the experiment or the participant knows if they are Treatment or Control
Note
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