The Effects of Commercial Electronic Variable Message Signs ...

A.3 KEY RESEARCH STRATEGIES
Table 3. Expanded key research strategies.
Method Ref. # Advantages Disadvantages
1.0 Crashes: Field 97, 95,
21
1.1 Unobtrusive observation
1.1.1 Participant: random,
uncontrolled; usually unknown
1.1.2 Experimenter: usually
absent; remote observation;
unknown to participant
1.1.3 Stimuli: natural, ordinary,
in context; variable,
uncontrolled
1.1.4 Responses: crashes;
antecedent vehicle behaviors;
rare; few participant variables
1.1.5 Scenario: natural route
and purpose; uses own vehicle
1.2 Naturalistic driving
1.2.1 Participant: selected,
sampled
1.2.2 Experimenter: absent;
remote observation; known to
participant
1.2.3 Stimuli: natural, ordinary,
in context; variable,
uncontrolled
1.2.4 Responses: crashes;
antecedent vehicle and
participant behaviors; rare
49 No sampling bias. Do not know participant sample.
49 No artificial participant
behaviors due to
experimenter.
49 Natural stimuli. Stimuli not uniform; e.g.,
weather effects.
49 Directly related to the safety
goal.
49 Completely natural
experimental context; uses
own vehicle.
79, 78,
42
79, 78,
42
79, 78,
64, 42
79, 78,
64, 42
53
Extremely rare events;
insensitive to participant
variables.
Long-term monitoring required.
Know participant sample. Possible sampling bias.
Possible artificial participant
behaviors.
Natural stimuli. Stimuli not uniform; e.g.,
weather effects.
Directly related to ultimate
goal; sensitive to some
participant variables.
Extremely rare events; difficult
to collect adequate sample of
crashes.