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Stat test 1
Test 1
35
Mathematics
Undergraduate 3
09/04/2013

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Term
Statistic
Definition
is a science that involves gathering information from numerical data obtained during an experiment or from a sample. It involves designing an experiment or sampling procedure, collecting the data, analyzing the data, and making inferences
Term
Population
Definition
The entire group of subjects or individuals about which the researcher wants information
Term
Parameter
Definition
Some characteristic of the population that the researcher wants to measure.
Term
Sample
Definition
A subset of the population that is contacted and examined to gather information.
Term
Statistic
Definition
A descriptive measure, computed from data in a sample, that can be expressed or evaluated numerically
Term
Inference
Definition
A statement about a population based on the data collected in a sample.
Term
Distribution
Definition
A listing of all the possible values that a characteristic can take and the number (or percentage) of times that each value occurs
Term
Descriptive Statistics
Definition
Branch of statistics concerned with numerical and graphical techniques for describing one or more characteristics of a population and for comparing characteristics among populations
Term
Inferential Statistics
Definition
Branch of statistics in which we use information from a sample to make inferences (statements) about a population.
Term
Constant
Definition
A characteristic whose value does not change throughout the population of interest.
Term
Variable
Definition
A characteristic whose measurements vary (or change) from trial to trial or individual to individual.
Term
Qualitative or Categorical Variable
Definition
A variable whose measurements vary in kind or name, but not in degree. This implies that one level of a categorical variable cannot be considered to be greater than or better than another level.
Term
Quantitative Variable
Definition
A variable whose measurements vary in magnitude from trial to trial, meaning some order or ranking can be applied to the levels.
Term
Discrete Quantitative Variable
Definition
A quantitative variable whose measurements can assume only a countable number of possible values.

Examples: 1. Number of students in a particular class
2. Number of cars in a parking deck
3. Grades on a test
Term
Continuous Quantitative Variable
Definition
A quantitative variable whose measurements can assume any one of a countless number of values in a line interval. It is usually a measurable quantity or something that is calculated, such as rates, averages, proportions, and percentages.

Examples: 1. Weight of a typical student
2. Percentage of students who pass a
course
Term
Bias
Definition
exists when some subjects or individuals are systematically favored over others.
Term
Selection Bias
Definition
occurs when one or more types of subjects are systematically excluded from the sample.
Term
Undercoverage
Definition
When selection bias exists, the results from the sample can only be inferred to part of the population. The inference cannot be made to the entire population, but only a subset of the population.
Term
Nonresponse Bias
Definition
When an individual randomly chosen to be a part of the sample cannot be contacted or fails (or refuses) to respond
Term
Response Bias
Definition
When respondents give inaccurate information or if the interviewer influences the subject to respond in a certain way due to the way the questions are phrased
Term
haphazard sample
Definition
involves selecting a sample by some convenient mechanism that does not involve randomization.

Ex: a mall survey
Term
volunteer response sample
Definition
subjects volunteer to be part of the study. Examples include telephone call-in polls, internet surveys, newspaper surveys, call in talk-show surveys, etc.
Term
Random sampling
Definition
Samples in which the subjects are chosen randomly to be in the sample are often representative of the population and are, for the most part, free of bias.
Term
probability sampling design
Definition
When each subject of the population has a positive and equal probability of being selected for the sample
Term
Stratified Random Sampling
Definition
The population is naturally divided into two or more groups of similar subjects
Term
Multistage Random Sampling
Definition
Instead of randomly selecting subjects from each group (as in stratified sampling), we randomly select (using simple random sampling) several of these groups.
Term
Experimental Units
Definition
the subjects (or individuals or units)
on which the measurements are
made.
Term
Treatment
Definition
an experimental condition applied to the
experimental units
Term
Response
Definition
the characteristic that is measured on each
experimental unit
Term
Treatment Group
Definition
the group or groups of experimental
units who receive the treatment(s
Term
Control Group
Definition
a group of experimental units who do not
receive the treatment, but instead receive
either a fake treatment or nothing at all
Term
Placebo
Definition
a fake treatment that is given to the experimental
units in the control group to prevent them from
knowing to which group they belong
Term
Confounding
Definition
When there exists some factor other than
the treatment that makes the treatment and
control groups different
Term
Controlled Experiment
Definition
The experimenter randomly selects experimental units to be in
the experiment and can control to which group each is assigned.
Term
Observational Studies
Definition
The experimenter observes the experimental units as they are.

They either cannot or do not control to which group each
experimental unit is assigned.

They do not impose the treatments (or placebo) on the
experimental units.
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