Systematic Observational systems follow various sampling and recording rules that are designed for different context and research questions. the following section contain review of central sampling and recording rules that quantitative scholars would use for conducting systematic observations. this section include strengths and weaknesses for each central sampling and recording approach.
Time Sampling
a time-dependent observational procedure in which the researcher a priori divides the behavior stream into discrete interval and each time interval is scored for the presence or absence of the behavior in question is defined as a time sampling observational approach. a time sampling procedure is an efficient method of sampling, as multiple data points may be collected from a single participant in a short period of time. time sampling is well suited for measuring rather discrete behaviors, such as overt behaviors or with behaviors that are frequently occuring. this procedure has strengths and weaknesses. the strengths of this approach is efficient and inexpensive, it is appropriate for frequently occuring and/or discrete behaviors. the weaknesses is less useful for infrequently occuring behaviors, time units may be categorized inappropriately.
Event Sampling
Event-based sampling also known as behavior sampling and permits a researcher to study the frequency, duration, latency and intensity of the behavior under study. essentially, unlike time sampling, event sampling is a type of observational sampling in which the event are time-dependent and the behavior is the unit of analysis. the strengths of this approach is efficiently enables the measurement of frequency, duration, latency, and intensity, it may be used with frequently or infrequently occuring behaviors. the weaknesses is it may be inappropriate in situations where it is difficult to determine the independence of events, such as dyadic interactions.
Participant Observation
Although participant observation has been more frequently used with nonsystematic field observation and in disciplines that focus on qualitative methods, it is possible to conduct systematic participant observation as part of quantitative studies. systematic participan observation has been the method of choice for behavior of interest that require "an insider's perspective" or for context in which the sampling period may be long and informal. the strengths of this method is appropriate for the study of broad and complex construct that encompass the variety of events or behaviors, it may be useful in applied settings. the weaknesses of course it's less efficient.
Focal Sampling
Focal person sampling involves selecting (typically at random from a roster of participants) one participant and observing the individual for a defined time period. for each sampling interval (ranges vary depending on the question of interests), the observer records all relevant behaviors of focal person. the strengths of this method allows for in-depth recording of an individual participant. continous recording enables multiple types, sequences, and true frequencies of behaviors, may be useful in applied research context. the weaknesses is large amount of time are often needed.
Scan Sampling
Instantaneous or scan sampling is a more efficient observational procedure than focal sampling. scan sampling exclusively relies on instantaneous recording rules. with this procedure the observer scans the entire observation field for a possible behavior or event for a particular period of time. if an event is noted during that scan, then it is recorded. strengths of this method instantaneous recording rules promote efficiency, it is appropriate for overt, readily observable behaviors. the weaknesses is it may be difficult to obtain true frequency of a behavior, it is less appropriate for subtle behaviors.