Stats Key Terms 1

Population

Population

total membership or “universe” of a defined class of people, objects or events.

Parameter

functions of the study variable values. They are unknown, quantitative measures for the entire population or for specified domains which are of interest to the investigator.

Samples

a subset of a frame where elements are selected based on a randomised process with a known probability of selection.

Statistic

any quantity computed from values in a sample which is considered for a statistical purpose

Population of Interest

the population from which the researcher wants to draw conclusions.

Population to which results can be generalized

a sample that accurately mirrors characteristics of the population.

Variable

characteristic of a unit being observed that may assume more than one of a set of values to which a numerical measure or a category from a classification can be assigned

Categorical

Data consisting of counts of observations falling in different categories. The categories may be purely descriptive, or may have a natural order.

Categorical ordinal

non-numerical pieces of information with implied order

Numeric Discrete

finite value that can be counted

Numeric Continuous

infinite number of possible values that can be measured

Associated

tells you whether two variables are related

Independent

if knowing one event occurred doesn't change the probability of the other event

Explanatory Variable

The variable that is used to explain or predict the response variable

Response Vaariable

a concept, idea, or quantity that someone wants to measure

Blocking Variable

the arranging of experimental units in groups that are similar to one another

Simple Random Variable

a generalization of the indicator random variable where instead of two events, N mutually exclusive events in that form a partition of Ω are mapped to N values in

Stratified Sampling

a method of sampling from a population which can be partitioned into subpopulations

Cluster Sampling

probability sampling method in which you divide a population into clusters, such as districts or schools, and then randomly select some of these clusters as your sample

Multistage Sampling

you draw a sample from a population using smaller and smaller groups at each stage.

Convenience Sampling

non-probability sampling that involves the sample being drawn from that part of the population that is close to hand

Voluntary Response

a sample made up of participants who have voluntarily chosen to participate as a part of the sample group

Sampling Bias

a bias in which a sample is collected in such a way that some members of the intended population have a lower or higher sampling probability than others

Observational Study

ones where researchers observe the effect of a risk factor, diagnostic test, treatment or other intervention without trying to change who is or isn't exposed to it

Expirement

any procedure that can be infinitely repeated and has a well-defined set of possible outcomes, known as the sample space

Retrospective Observational Study

non-randomised, non-interventional analyses of existing data relating to patients, care received and outcomes

Prospective Observational Study

individuals are followed over time and data about them is collected as their characteristics or circumstances change

Control

the application of statistical methods to monitor and control the quality of a production proces

Placebo

an inactive substance that looks like the drug or treatment being tested

Blind Experiment

practice where study participants are prevented from knowing certain information that may somehow influence them—thereby tainting the results

Double Blind Expirement

requires that both researchers and test subjects are unaware of who is receiving the treatment and who is receiving the placebo