Data: Someone has died from a selfinflicted gunshot wound'

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Data Someone has died from a self-inflicted
gunshot wound. WHY?
Possible reasons (THEORIES)
1. Suicide 2. Accident Test between the
theories gather more evidence (DATA)
Suggest a hypothesis If suicide, then there may
be a suicide note. No note.
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Can we infer the mental state at time of
incident? Family history of depression Friends
on drugs Girlfriend recently left him
There are gun-cleaning supplies in room
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INDUCTION Working from specific data to form a
theory Detectives on the scene gather all of
the facts, then theory DEDUCTION Working from
a theory to predict data Friend at home
personal opinion, then read facts (data) to
verify
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Psychology is a young science (about 100 years
or so) Began with Wundt (approached questions in
a scientific way)
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Scientific Method An approach/philosophy Goals
Description Procedures by which events and
relationships are defined, classified,
cataloged or categorized Prediction Future
events Understanding Achieved when causes of a
phenomenon are identified Causal inference
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3 characteristics for causal inference 1.
Covariation of events 2. Time-Order
relationship Presumed cause precedes presumed
effect 3. Elimination of plausible alternative
causes
One problem People often accept as cause when
only 1st condition is met Stern disciplinarians
are likely to have aggressive children
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General Approach Empirical Based on
experience, not faith, intuition Observation Sys
tematic Controlled Look at effect of factors
on behavior Independent variables Factors
explored by researcher Individual difference
variables Factor whose levels are selected
(given by participant) (e.g., age, gender,
height) Manipulated variables Factor whose
levels are defined by experimenter (e.g.,
repetitions of a task, dosages of a
drug) Dependent variables Measures of
behavior used to assess effects of
indep.variables (if any) (e.g., looking
behavior, response times, accuracy)
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Reporting Description not inferences Unbiased
and objective can it be verified? Concepts Op
erational definitions Define a concept only in
terms of the operations used to produce and
measure it. Instruments Accurate What an
instrument says is true, relative to
a standard (known to be true) use
calibration Precise Levels of measurement
(varying degrees) Measurement Valid
Truthfulness does it measure what it says it
is measuring? Reliable Consistency same
result time and time again?
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Hypotheses Tentative explanations that are
testable Possible to prove wrong Theory A
logically organized set of ideas which serves to
define events (concepts), describe
relationships among these events, and explain
the occurrence of these events. Scope Source
Language Assessing theories 1. Logical
consistency free of contradictions? 2.
Explicitly test hypotheses derived using
scientific method Theories produce of
hypotheses. Any given hypothesis
weakens/strengthens a theory One failure usually
does not disconfirm theory 3. Parsimony Is
this the simplest theory that accounts for
data? Beware trade-off between parsimony and
precision of predictions