Ch. 1 Statistics (what is statistics)

Single-Stage Sampling

a sample design in which the elements of the sampling frame are treated equally and there is no subdividing or partitioning of the frame

Unbiased Sampling Method

a sampling method that is not biased and produces data that are representatives of the sampled population

Biased sampling method

a sampling method that produces data that systematically differ from the sampled population. repeated sampling will not correct the bias

Parameter *(population)

A numerical value summarizing all the data of an entire population

Statistic

A numerical value summarizing the sample data

Experiment

A planned activity whose results yield a set of data.

Finite Population

A population whose membership can or could be physically listed.

Systematic Sample

A sample in which every kth item of the sampling frame is selected, starting from a first element, which is randomly selected from the first k elements.

Stratified Random Sample

A sample obtained by stratifying the population, or sampling frame, and then selecting a number of items from each of the strata by means of a simple random sampling technique.

Proportional stratified Sample

A sample obtained by stratifying the population, or sampling from, and then selecting a number of items in proportion to the size of the strata from each strata by means of a simple random sampling technique

Cluster Sample

A sample obtained by stratifying the population, or sampling from, and then selecting some or all of the items from some, but not all, of the strata

Simple Random Sample

A sample selected in such a way that every element in the population or sampling frame has an equal probability of being chosen. Equivalently, all samples of size n have an equal chance of being selected.

Sample Design

A selection process in which a "representative" sampling frame has been established. We now select the sample elements from the sampling frame.

Population

A collection, or set, of individuals, objects, or events whose properties are to be analyzed

Strata

A large population that has been divided on the basis of some characteristic

Sample

A subset of a population

Continuous Variable

A variable (such as age, test score, or height) that can take on a wide or infinite number of values.

Qualitative Variable (or attribute, or categorical variable)

A variable that describes or categorizes an element of a population

Attribute variable AKA qualitative/Categorical

A variable that describes or categorizes an element of a population Ex: hair color, hometown, or level of satisfaction

Categorical Variable

A variable that describes or categorizes an element of a population Ex: hair color, hometown, or level of satisfaction

Quantitative Variable or (Numerical, variable)

A variable that quantifies an element of a population *includes a number

Census

Compiled when every element in the population can be listed, or enumerated, and observed.

Probability Sample

Samples in which the elements to be selected are drawn on the basis of probability. Each element in a population has a certian probability of being selected as part of the sample.

Representative

Ex: census / Because only the elements in the frame have a chance to be selected as part of the sample it is important that the smampling frame be "representative" of the population

Judgment Sample

Samples that are selected on the basis of being judged "typical".

Multistage Random Sampling

a sample design in which the elements of the sampling frame are subdivided and the sample is chosen in more than one stage

Descriptive Statistics

Includes the collection, presentation, and description of sample data.

Observational Study

Investigator does not modify the environment and does not control the process being observed

Convenience Sample AKA Grab sample

Items are chosen arbitrarily and in an unstructured manner from a population

Survey

Observational studies of people

Variable (or response variable)

The aspect of a population that we study. A characterisitic of interest about each inidividual element of a population or sample

Sampling Method

The process of selecting items or events that will become the sample

Statistics

The science of collecting, describing, and interpreting data

Data

The set of values collected from the variable from each of the elements that belong to the sample. Once all the data are collected, it is common practice to refer to the set of data as the sample.

Inferential Statistics

The technique of interpreting the values resulting from the descriptive techniques and making decisions & drawing conclusions about the population

Data Value

The value of the variable associated with one element of a population or sample. This value may be a number, a word, or a symbol.

Discrete Variable

a quantitative variable whose values are countable

Infinite population

When membership is unlimited

Haphazard

Without pattern *do not confuse with random sample

Sampling Frame

a list, or set, of the elements belonging to the population from whom the sample is drawn

Nominal Variable

a qualitative variable that categorizes an element of a population. Not only are arithmetic operations not meaningful for data that result from a nominal variable, but also an order cannot be assigned to the categories

Ordinal Variable

a qualitative variable that incorporates an ordered position, or ranking

Data collection

methods that will produce data that are representative of the population and not biased.

Variability

the frequency and extent to which multiple measures of behavior yield different outcomes Ex: weight of candy bars

Volunteer Sample

the information needed is collected from those elements of the population that chose to contribute on their own initiative.