ASTM_D_5791_-_95_2012e1.pdf

Designation:D579195(Reapproved 2012)1Standard Guide forUsing Probability Sampling Methods in Studies of Indoor AirQuality in Buildings1This standard is issued under the fixed designation D5791;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEReapproved with editorial changes in April 2012.1.Scope1.1 This guide covers criteria for determining when prob-ability sampling methods should be used to select locations forplacement of environmental monitoring equipment in a build-ing or to select a sample of building occupants for question-naire administration for a study of indoor air quality.Some ofthe basic probability sampling methods that are applicable forthese types of studies are introduced.1.2 Probability sampling refers to statistical sampling meth-ods that select units for observation with known probabilities(including probabilities equal to one for a census)so thatstatistically defensible inferences are supported from thesample to the entire population of units that had a positiveprobability of being selected into the sample.1.3 This guide describes those situations in which probabil-ity sampling methods are needed for a scientific study of theindoor air quality in a building.For those situations for whichprobability sampling methods are recommended,guidance isprovided on how to implement probability sampling methods,including obstacles that may arise.Examples of their applica-tion are provided for selected situations.Because some indoorair quality investigations may require application of complex,multistage,survey sampling procedures and because this stan-dard is a guide rather than a practice,the references inAppendix X1 are recommended for guidance on appropriateprobability sampling methods,rather than including exposi-tions of such methods in this guide.1.4 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.2.Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheres3.Terminology3.1 DefinitionsFor definitions of terms used in this guide,refer to Terminology D1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 censussurvey of all elements of the target popula-tion.3.2.2 cluster samplea sample in which the sampling frameis partitioned into disjoint subsets called clusters and a sampleof the clusters is selected.3.2.2.1 DiscussionData may be collected for all units ineach sample cluster or,when a multistage sample is beingselected,the units within the sampled clusters may be furthersubsampled.3.2.3 compositing samplesphysically combining the ma-terial collected in two or more environmental samples.3.2.4 expected valuethe average value of a sample statis-tic over all possible samples that could be selected using aspecified sample selection procedure.3.2.5 multistage samplea sample selected in stages suchthat larger units are selected at the first stage,and smaller unitsare selected at each subsequent stage from within the unitsselected at the previous stage of sampling.3.2.5.1 DiscussionFor assessing the indoor air quality in apopulation of office buildings,individual buildings might beselected at the first stage of sampling,floors selected within1This guide is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.05 on Indoor Air.Current edition approved April 1,2012.Published July 2012.Originallyapproved in 1995.Last previous edition approved in 2006 as D5791-95(2006).DOI:10.1520/D5791-95R12E01.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 sample buildings at the second stage,and monitoring locations(for example,rooms or grid points)selected on sampled floorsat the third stage.3.2.6 population parametera characteristic based on orcalculated from all units in the target population.3.2.6.1 DiscussionThe purpose of selecting a sample isusually to estimate population parameters.Population param-eters cannot actually be calculated unless data are available forall units in the population.3.2.7 probability samplea sample for which every unit onthe sampling frame has a known,positive probability of beingselected into the sample.3.2.7.1 DiscussionThe terms probability sampling andrandom sampling are sometimes used interchangeably.3.2.8 sampling framea list from which a sample is se-lected.3.2.8.1 DiscussionAn ideal sampling frame contains eachmember of the target population exactly once and