1
Introduction
to
Psych 100A
Fall 2010
Statistics
Lecture 2
1
Types of research designs
•
What type of research design is this study?
• Choices:
–Naturalistic observation = observing
behaviors without any intervention
–Archival record = using existing information
(already recorded observations)
–Survey = collecting responses of a group of
individuals
–Experiment = carefully controlled situation
where the independent variable is manipulated
and the effect on the dependent variable is
monitored.
2
•
Quantitative Data.
The usual table of choice is the frequency
table.
•
Data presented in simplified form as
grouped data.
•
Number of groups or class intervals are
decided by common sense and good
judgment (e.g. 620 groups).
•
Implied limits are the boundaries or
endpoints of the class intervals and
depend on the convention for rounding.
3
•
Frequency table (continued).
•
Number of observations in each class
interval is the frequency.
•
The relative frequency is the frequency
divided by the total (usually multiplied
by 100%)
by 100%).
•
The cumulative relative frequency for a
given interval is the sum of the relative
frequencies of the intervals that
precede it plus the relative frequency of
the given interval.
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 Winter '10
 FIRSTENBERG,I.
 Frequency distribution, Histogram, class interval

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