OK, I told you that this is a course in communication. Like any language course, you’re going to
have to learn to speak the language. Prepare to master a lot of jargon!
Datum
A single measurement or observation, commonly called a score or a raw score.
Data
Plural of datum, measurements or observations
Data set
Collection of measurements or observations
Population
Sample
The set of all the individuals of interest in a
particular study.
A set of individuals selected from a population,
usually intended to represent the population in
a research study.
A
parameter
is a value that describes a
population. (Greek letter:
σ
,
ρ
)
A
statistic
is a value that describes a sample.
(English letter:
s
,
r
)
Define a
population that you
might want to
study.
Random sampling
A process for obtaining a sample from a population that requires that every
individual in the population has the same chance of being selected for the
sample.
What procedure would you use
to obtain a sample from your
population so that it would be
representative?
One is rarely interested in simply describing a sample, but if that were all that you want to do,
you would compute
descriptive statistics
(procedures used to summarize, organize, and simplify
data). It’s much more common for one to be interested in using the sample to make inferences
about the population.
Inferential statistics
consist of techniques that allow us to study samples
and then make generalizations about the populations from which they were sampled.
Why would you select a sample? Why not just
collect data from the entire population?
Could you compute inferential statistics on a
population? Why or why not?
Ch1  1
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 Spring '11
 bcd
 Level of measurement, operational definition, continuous variable

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