Transcript Notes

Psychology Chapter 1
Section 7: Evaluating
Findings
 Once
you have some results in
hand you must do 3 things
 Describe them
 Assess how reliable &
meaningful they are
 Figure out how to explain them
Why do psychologists use
statistics?
 What
do you do with the numbers
or scores you collect?
 Use descriptive statistics:
Organize and summarize data
 Often depicted in charts &
graphs
 Compute
group averages
 Arithmetic mean
 Calculate by adding up all the
individual scores & dividing the
result by the total number of scores
 Mean does not tell you about such
variability in the subjects
responses
 Need
standard deviation- tells you
how clustered or spread out the
individual scores are around the
mean
 The more spread out they are, the
less “typical” the mean is
 To
find out how impressive the data
are, psychologists use inferential
statistics
 Assess how meaningful results are,
such as differences between groups
 Significance tests assess how likely
it is that a study’s results occurred
merely by chance
 If
the likelihood that a result occurred
by chance is extremely low, that is
called statistically significant
 The probability that the difference is
“real” is overwhelming
 Psychologists consider a result
significant if it would be expected to
occur by chance 5 or fewer times in
100 repetitions of the study
From the Lab to the Real World
 Last
step is to figure out what
the findings mean
Choosing the best Explanation
Sometimes there are competing
explanations for the same events
 Must not go too far beyond the facts
 Several explanations may fit those facts
well, which means that more research
will be needed to determine the best one
 Sometimes that doesn’t emerge until a
hypothesis has been tested in different
ways

Judging the result’s Importance
Statistical significance does not prove that
a result is important, only that it is reliable
 Many psychologists prefer other statistical
procedures that reveal how powerful the
IV really is & how much of the variation in
the data the variable accounts for
 Meta-analysis combines and analyzes
data from many studies

 Tells
the researcher how much of the
variation in scores across the studies
examined can be explained by a
particular variable
Different Research Methods
 Cross-Sectional
Study: Subjects of
different ages are compared at a
given time.
 Longitudinal Study: Subjects are
followed & periodically reassessed
over a period of time
 Be
suspicious
of headlines
that announce
a sudden,
major scientific
breakthrough
based on a
single study
Assignment
 Read
Taking Psychology
With You on page 33