Scan Sampling
Scan Sampling Behavioral Observation Method · Also known as: instantaneous sampling, scan observation, group sampling
Scan Sampling (also called instantaneous sampling) is a behavioral observation method in which an observer records the state of all group members simultaneously at regular time intervals. Introduced alongside focal animal sampling by Jeanne Altmann in 1974, scan sampling is efficient for quantifying activity budgets and group-level behavioral patterns in multiple animals without the labor of focal observation.
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When to use it
Scan sampling is applied to efficiently survey large groups where focal observation is impractical (e.g., 30+ individuals). It is valuable for rapid assessment of group activity budgets, identifying behavioral changes in response to management interventions (space enlargement, enrichment), and longitudinal monitoring of behavior patterns with minimal resource investment. Scan sampling is particularly useful in field studies of wild groups where animals move frequently and group membership is fluid.
Strengths & limitations
- Efficient: observer can sample many animals and many observation sessions, generating large sample sizes with modest effort
- Quantifies group-level behavioral patterns and individual variation within groups
- Low cost and minimal equipment requirements
- Non-invasive and low disturbance to animals; observer can remain distant and inconspicuous
- Enables long-term monitoring studies unfeasible with focal sampling
- Loses temporal information: no data on behavior sequences, transitions, or durations within single behavioral states
- Sensitive to scan interval choice: too-short intervals (e.g., 30 seconds) introduce redundancy; too-long intervals (e.g., 2 hours) miss behavior changes
- Simultaneous behavior classification challenging in large groups; observer error and synchronization bias are common
- Rare behaviors underrepresented unless scan intervals are very short, inflating time spent on common activities
- Mobile or cryptic animals may be missed at scan points, biasing activity budget away from actual behavior
Frequently asked
How often should scans be conducted?
Scan interval depends on behavior speed and research question. Rapidly changing behaviors (e.g., feeding in birds) require shorter intervals (2-5 minutes); slower behaviors (e.g., rest, sleeping) permit longer intervals (30-60 minutes). Pilot observations can reveal appropriate intervals; interval should be shorter than average behavior duration.
Can scan sampling capture rare behaviors?
Poorly. Rare behaviors require either very short scan intervals (increasing observer workload) or very long observation sessions. For detailed study of rare behaviors, focal animal sampling or all-occurrence sampling (recording all instances of target behavior) is more appropriate.
What is the 'observer effect' in scan sampling?
Observer presence can alter behavior. Animals may hide, freeze, or move away from the observer. Scan sampling reduces this effect compared to focal sampling because the observer is not obviously focusing on individuals. Habituation time before observations begin minimizes this problem.
How should 'not visible' observations be handled?
Record them separately. Analyses should note the proportion of scans in which all animals were visible. If visibility is consistently low (e.g., <80%), results are less reliable. Some researchers exclude 'not visible' animals from analysis, which biases results away from hidden behaviors (e.g., hiding, sleeping in shelters).
Sources
- Altmann, J. (1974). Observational study of behavior: sampling methods. Behaviour, 49(3-4), 227-267. DOI: 10.1163/156853974X00534 ↗
- Martin, P., & Bateson, P. P. (1993). Measuring Behaviour: An Introductory Guide (2nd ed.). Cambridge University Press. link ↗
- Coad, N., Al-Rasheid, K. A., & Sluydts, V. (2002). Instantaneous sampling of group-living primates. Primates, 43(2), 105-110. link ↗
How to cite this page
ScholarGate. (2026, June 3). Scan Sampling Behavioral Observation Method. ScholarGate. https://scholargate.app/en/veterinary-science/scan-sampling
Which method?
Set this method beside its closest kin and read them side by side — the library lays the books on the table; the choice is yours.
- Equine Gait AnalysisVeterinary Science↔ compare
- Focal Animal SamplingVeterinary Science↔ compare
- PolysomnographyVeterinary Science↔ compare