Ch. 1 : The What and How of Statistics
A.
Statistical Analysis –
collection, organization, and interpretation of data
according to welldefined procedures.
o
Variable –
anything that can vary
o
Data –
information about different variables
o
Data Distribution –
when data are assembled and put together in a list
B. Levels of Measurement
o
NOMINAL level of measurement
categories must be
mutually exclusive
: answers cannot be placed
into more than one category
categories must be
collectively exhaustive:
you have to have a
category for every observation or case that you’re classifying or
recording
o
ORDINAL level of measurement
Must be some notion of
order
or a way to measure more/less than
EX. Levels of education (high school
postcollege… or
anywhere inbetween)
o
INTERVAL level of measurement
Notion of
equal intervals
in measurement
EX. Asking people to tell you their age at their last birthday
o
RATIO level of measurement (sometimes simply combined with
interval)
has all the properties of the interval level of measurement BUT the
ratio level has a true or known ZERO point
EX. How many hours of TV you watch a day
Zero is a “legitimate” answer
**NOTE** some cases that appear to be RATIO are actually
INTERVAL. EX. A zero on a thermometer doesn’t represent and
ABSENCE of any temperature
C. Samples and Populations
o
Population (
or
universe) –
all possible cases that meet certain criteria
PROBLEMS
•
Constant state of flux
•
Difficulty in having access to an entire population
•
therefore samples are used as a substitute for the entire
population
o
Sample
– a portion of a population
Being representative
means that the sample has a similar ratio as
the population.
•
EX.
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 Spring '10
 Cleveland
 Standard Deviation, Mean, Populations o Population, Statistics A. Statistical Analysis

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