Data and Statistics

Data and Statistics:

Data: consists of information coming from observations, counts, measurements, or responses.

Statistics is the science of collecting, organizing, analyzing, and interpreting data in order to make decisions.

population

                 is the collection of all outcomes, responses, measurement, or counts that are of interest.

sample 

                 is a subset of a population.

Methods of Data Collection:

´  In an observational study, a researcher observes and measures characteristics of interest of part of a population.

´  In an experiment, a treatment is applied to part of a population, and responses are observed.

´  A simulation is the use of a mathematical or physical model to reproduce the conditions of a situation or process.

´  A survey is an investigation of one or more characteristics of a population.

´  A census is a measurement of an entire population.

´   A sampling is a measurement of part of a population.

Types of Samples:

 Stratified Samples :

A stratified sample has members from each segment of a population.  This ensures that each segment from the population is represented.

      Cluster Samples:

A cluster sample has all members from randomly selected  segments of a population.  This is used when the population falls into naturally occurring subgroups.

Systematic Samples:

A systematic sample is a sample in which each member of the population is assigned a number.  A starting number is randomly selected and sample members are selected at regular intervals.

         Convenience Samples:

A convenience sample consists only of available members of the population.