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THINKING CRITICALLY:
THINKING CRITICALLY:
Part 2
Part 2
Ψ
100
100
Sep 22
Sep 22 ‘
08
08
Overview
Overview
Define statistics & difference between descriptive
& inferential
Common measuring scales and what we can do
with them
Shapes of distributions
Measures of central tendency (of the centre of a
distribution)
Measures of dispersion (of the spread of a
distribution)
Correlations (strength, direction)
Lying with statistics
Learning Objectives
Learning Objectives
Define statistics & difference between descriptive & inferential
Understand the following measuring scales: nominal, ordinal, interval & ratio
Understand what kinds of statistics are permissible with data from each
scale
Explain how graphs can be used to misrepresent data
Describe and use three measures of central tendency, and tell which is most
affected by extreme scores
Describe and use two measures of variability: range & standard deviation
Identify factors that affect generalizability of findings
Explain how psychologists decide whether differences are meaningful;
understand the difference between statistical significance and practical
significance
Explain the value of simplified laboratory conditions in discovering general
principles of behavior
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Statistics is/are
Statistics is/are
The mathematics of the collection, organization, and
interpretation of numerical data, especially the analysis of
population characteristics by inference from sampling
A branch of mathematics dealing with the collection,
analysis, interpretation, and presentation of masses of
numerical data
A set of data (i.e. vital statistics)
Three kind of lies: ‘Lies, damned lies, and statistics.’
Types of Statistics
Types of Statistics
Inferential Statistics:
A set of procedures for making decisions about hypotheses.
A set of procedures for reaching conclusions that extend beyond
the data. These procedures help us make inferences from the
sample about the population from which it was drawn.
Descriptive Statistics:
Descriptive statistics are simple descriptions of what the data
show; they are quantitative or pictorial summaries of the data.
Descriptive statistics refers to a set of procedures /methods
used for describing the basic features of the data in a study.
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 Fall '09
 PETERGRAF
 Statistics, Standard Deviation, Descriptive statistics, highest value minus

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