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CH 7-11 of POLS Research Methodology

### Cluster Sample

A probability sample that is used when no list of elements exists. the sampling frame initially consists of clusters of elements

### Convenience Sample

a nonprobability sample in which he selection of elements is determined by the researcher's convinience

### cumulative proportion

the total proportion of observations at or below a value in a frequency distribution

### data matrix

an array of rows and columns that stores the values of a set of variables for all the cases in a data set

### descriptive statistic

a number that, because of its definition and formula, describes certain characteristics or properties of a batch of numbers

### Episodic Records

Record that is not part of a regular, ongoing record-keeping enterprise but instead is produced and preserved in a more casual, personal, or accidental manner

### Estimator (μ or p)

A statistic based on sample observations that is used to estimate the numerical value of an unknown population parameter

### Expected Value

the mean or average value of a sample statistic based on repeated samples from a population

### Indirect Observation

observation of physical traces of behavior. May misinterpret data, but do not affect the things being studied

### informant

persons who are willing to be interviewed about the activities and behavior of themselves and of the group to which they belong. They also help the researcher engaged in participant observation to interpret group behavior.

### Informed Consent

Procedures that inform potential research subjects about the proposed research in which they are being asked to participate; the principle that researchers must obtain the freely given consent of human subjects before they particitare in a research project

### Institutional Review Board (IRB)

Panel to which researchers must submit descriptions of proposed research involving human subjects for the purpose of ethics review

### Intercoder Reliability

demonstration that multiple analysts, following the same content analysis procedure, agree and obtain the same measurements

### Margin of Error

The difference between a sample estimate and a corresponding population parameter that arises because only a portion of a population is observed

### negatively skewed

a distribution of values in which fewer observations lie to the left of the middle value and thaaose observations are fairly distant from the mean

### Nonprobability sample

a sample for which each element in the total population has an unknown probability of being selected

Purposive Sample

Convenience Sample

Quota Sample

Snowball Sample

### Participant Observation

observations in which the observer becomes a regular participant in the activities of those being observed

### Population Parameter (θ or P)

A characteristic or an attribute in a population (not a sample) that can be quantified.

### positively skewed

a distribution of values in which fewer observations lie to the right of the middle value and thaaose observations are fairly distant from the mean

### Probability sample

a sample for which each element in the total population has a known probability of being selected

Simple Random Sample

Systematic Sample

Stratified Sample

Cluster Sample

### Purposive Sample

a nonprobability sample in which a researcher uses discretion in selecting elements for observation

### Push poll

a poll intended not to collect information, but to feed respondents (often) false and damaging information about a candidate or cause

### Quota Sample

A nonprobability sample in which elements are sampled in proportion to their representation in the population

### relative frequency

proportion of total number of observations in a frequency distribution that have a particular value

### resistant measure

a measure of central tendency that is not sensitive to one or a few extreme values in a distribution

### Response Rate

the proportion of respondents selected for participation in a survey who actually participate

### Response Set

the pattern of responding to a series of questions in a similar fashion without careful reading of each question

### Running Records

A written record that is enduring and easily accessed and covers and extensive period of time. Useful in observing changes, low costs

### Sample

Any subset of units collected in some manner from a population. (The selection of the population selected for the study)

### Sample bias

occurs whenever some elements of a population are systematically excluded from a sample. it is usually due to an incomplete sampling frame or a nonprobability method of selecting elements

### Sample-Population Congruence

The degree to which sample subjects represent the population from which they are drawn

### Sampling Distribution

A theoretical (non-observed) distribution of sample statistics calculated on samples of size N that, if know, permits the calculation of confidence intervals and the test of statistical hypotheses. Measure the mean, variations, and shape of distribution

### Sampling Frame

The population from which the sample is drawn. Ideally, it is the same as the total population of interest to a study

### Sampling unit

The entity listed in a sampling frame. it may be the same as an element or it may be a group or cluster of elements

### semi-structured interview

An interview guide is provided, giving previous knowledge if the questions being asked and in what order

### Simple Random Sample

A probability sample in which each element has an equal chance of being selected

### Single-sided question

a question in which the respondent is asked to agree with a single substantive statement

### Snowball Sample

A sample in which respondents are asked to identify additional members of the population

### standard deviation

a measure of dispersion of data points about the mean for interval and ratio related data. difference between each score and the mean, averaged

### Standard Error

the standard deviation or measure of variability or dispersion of a sampling distribution. Increasing the sample size reduces this by raising confidence in having the true mean

### Statistical inference

the mathematical theory and techniques for making conjectures about he unknown characteristics (parameters) of populations based on samples

### Stratified Sample

A probability sample in which elements sharing one or more characteristics are grouped and elements are selected from each group in proportion to the group's representation in the total population

### Systematic Sample

A probability sample in which elements are selected from a list at predetermined intervals

### trimmed mean

the mean calculated by excluding a specified proportion of cases from each end of the distribution

### Validity, Reactivity, Cost and availability of data

Considerations for selecting a method for collecting data

### variance

a measure of dispersion of data points about hte mean for interval and ratio level data. the average of squared deviations