Population (statistics)
A population is the complete group of every individual that satisfies the attributes of interest.
Parameter
Information that is calculated using every person in a population is called a parameter.
Sampling
Sampling is the selection of a subset (a statistical sample) of individuals from within a statistical population to estimate characteristics of the whole population.
Sample
A sample is any group taken from a population that does not include all individuals from the population.
Is a sample necessarily representative of the population?
Ideally, yes
In practice, sometimes samples are not representative. this is the result of sampling bias.
Statistic
Information about a sample is called a statistic.
Sample is to population as statistic is to _____.
parameter
With comparatively large or repeated samples, statistics can be used to _____.
estimate population parameters
Internal validity
Internal validity is the tendency of the same experiment to produce the same results when repeated, and provides support for causality.
External validity
External validity, or Generalizability, is the extent to which you can generalize the findings of a study to other situations, people, settings, and measures.
Studies with low generalizability have _____, while studies with high generalizability have samples that are _____.
very narrow conditions for sample selection that do not reflect the target population
representative of the target population
Drugs undergo continuous evaluation in part because of _____.
poor preclinical generalizability
Statistical significance
A result has statistical significance when a result at least as "extreme" would be very infrequent if the null hypothesis were true.
Clinical significance
The practical importance of a treatment effect—whether it has a real genuine, palpable, noticeable effect on daily life.
For example, a decrease in systolic blood pressure of one millimeter of mercury could be statistically significant; however, it is not likely to change patient outcomes.
Establishing a parameter is generally _____ for large populations.
not feasible