Chpt 1: Statistics and Samples Flashcards
What is a population?
All individuals in the world
What is a sample?
A subset of a population that we collect and analyze
What is a parameter?
Something that describes a population
Do we always know the parameters of a population?
No, but we can use estimates from samples to get a sense of a populations parameters
Are parameters fixed?
Yes, parameters are constant
Are estimates fixed?
No, they are random variables and change from one sample to the next within the same population
What is sampling bias?
When there is a systematic difference between estimates and parameters
What is sampling error?
When there is an undirected deviation of estimates away from parameters (sampling error is indicative of precision; the lower the sampling error, the higher the precision)
When does sampling bias arise?
When the sample is not truly representative of a population ex. The 1936 election results vs questionnaire results
What makes a good sample?
When each member of a population has an independent and equal chance of being selected
What are the two major types of variables?
Numeric and Categorical
What are the two types of numeric variables?
Discrete and Continuous
What is a discrete variable?
A variable that can only take some values ex. Age
What is a continuous variable?
A variable that can take any value ex. Core body temperature
What are the two types of categorical variables?
Ordinal and Nominal
