In statistics , a simple random sample (or SRS ) is a subset of individuals (a sample ) chosen from a larger set (a population ) in which a subset of individuals are chosen randomly , all with the same probability. It is a process of selecting a sample in a random way. In SRS, each subset of k individuals has the same probability of being chosen for the sample as any other subset of k individuals. Simple random sampling is a basic type of sampling and can be a component of other more complex sampling methods.
36-507: [REDACTED] Look up SRS in Wiktionary, the free dictionary. SRS or SrS may stand for: Organizations and companies [ edit ] Savez Radio-Amatera Srbije , a Serbian amateur radio organization Sea Ranger Service , a social enterprise managing ocean areas Sea Research Society , for diving and underwater archaeology Serbian Radical Party ( Srpska radikalna stranka ),
72-559: A 1 in 10 chance of being selected using this method. Further, any combination of 100 students has the same probability of selection. If a systematic pattern is introduced into random sampling, it is referred to as "systematic (random) sampling". An example would be if the students in the school had numbers attached to their names ranging from 0001 to 1000, and we chose a random starting point, e.g. 0533, and then picked every 10th name thereafter to give us our sample of 100 (starting over with 0003 after reaching 0993). In this sense, this technique
108-585: A British society to maintain and share knowledge of Railway Signalling and Operation in the British Isles and Overseas. Special Repair Service , a British construction organization in World War II Stanford Research Systems , a test and measurement instruments manufacturer Scoliosis Research Society Socialist Revolutionary Party , or "Essers", from the late Imperial and early Soviet periods Society for Renaissance Studies ,
144-481: A Japanese role-playing game system SRS (sailing) , a handicapping system 1st Strategic Reconnaissance Squadron , in the US Air Force Security Response Section , a unit of South Australia Police Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title SRS . If an internal link led you here, you may wish to change
180-629: A UK-based academic society Spanish Riding School , an Austrian equestrian institution Sperry Rail Service , a rail inspection contractor SRS Cinemas , in India SRS Labs , an American audio technology engineering company Surveillance and Response Support, a unit of the European Centre for Disease Prevention and Control Southwick Regional School , a public high school in Massachusetts, United States Suffolk Records Society , in
216-407: A US Department of Energy nuclear facility Selhurst railway station , London, England, National Rail station code Social Reporting Standard , a method of reporting business responsibility Stealth Recon Scout , a sniper rifle made by Desert Tech Standard RPG System , a Japanese role-playing game system SRS (sailing) , a handicapping system 1st Strategic Reconnaissance Squadron , in
252-403: A better choice. A sampling method for which each individual unit has the same chance of being selected is called equal probability sampling (epsem for short). Using a simple random sample will always lead to an epsem, but not all epsem samples are SRS. For example, if a teacher has a class arranged in 5 rows of 6 columns and she wants to take a random sample of 5 students she might pick one of
288-496: A document of a software system to be developed Street Racing Syndicate , a video game Spaced repetition software, a learning tool Technology [ edit ] Cirrus SRS , a light-sport aircraft Sound Retrieval System , an audio processing technology Space research service , a radiocommunication service using spacecraft or other objects in space Spatial reference system , used to locate geographical entities by coordinate Supplementary Restraint System ,
324-408: A fair way to see who gets to go. Then, everybody is given a number in the range from 0 to N -1, and random numbers are generated, either electronically or from a table of random numbers. Numbers outside the range from 0 to N -1 are ignored, as are any numbers previously selected. The first X numbers would identify the lucky ticket winners. In small populations and often in large ones, such sampling
360-705: A genetic disorder Spontaneous reporting system , a reporting system for drug adverse reactions Stereotactic radiosurgery Math, science, and technology [ edit ] Science [ edit ] Shock response spectrum , a graphical representation of vibrations Spontaneous Raman spectroscopy Stimulated Raman spectroscopy , the inelastic scattering of photons String rewriting system , in computer science and mathematical logic Strontium sulfide (SrS), an inorganic compound Synchrotron Radiation Source , an X-ray facility in Cheshire, England Mathematics [ edit ] Simple random sample ,
396-516: A learning tool Technology [ edit ] Cirrus SRS , a light-sport aircraft Sound Retrieval System , an audio processing technology Space research service , a radiocommunication service using spacecraft or other objects in space Spatial reference system , used to locate geographical entities by coordinate Supplementary Restraint System , a type of automobile airbag Other uses [ edit ] Sample Registration System, Indian demographic survey Savannah River Site ,
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#1732844201200432-506: A measure of autistic traits Somatostatin receptor scintigraphy , used to find carcinoid and other types of tumors Snyder–Robinson syndrome , a genetic disorder Spontaneous reporting system , a reporting system for drug adverse reactions Stereotactic radiosurgery Math, science, and technology [ edit ] Science [ edit ] Shock response spectrum , a graphical representation of vibrations Spontaneous Raman spectroscopy Stimulated Raman spectroscopy ,
468-424: A method of sampling in statistics Stratified random sample , a related method of sampling Software [ edit ] Sender Rewriting Scheme , an email mechanism Sequence Retrieval System , bioinformatic software by LION Bioscience AG Software requirements specification , a document of a software system to be developed Street Racing Syndicate , a video game Spaced repetition software,
504-502: A political party in Serbia Signalling Record Society , a British society to maintain and share knowledge of Railway Signalling and Operation in the British Isles and Overseas. Special Repair Service , a British construction organization in World War II Stanford Research Systems , a test and measurement instruments manufacturer Scoliosis Research Society Socialist Revolutionary Party , or "Essers", from
540-460: A public high school in Massachusetts, United States Suffolk Records Society , in the UK Medicine [ edit ] Sex reassignment surgery , now called gender-affirming surgery Silver–Russell syndrome , a growth disorder Slipping rib syndrome , a painful condition affecting the ribs Slow-reacting substance of anaphylaxis , a type of secretion Social Responsiveness Scale ,
576-412: A small sample from a large population, sampling without replacement is approximately the same as sampling with replacement, since the probability of choosing the same individual twice is low. Survey methodology textbooks generally consider simple random sampling without replacement as the benchmark to compute the relative efficiency of other sampling approaches. An unbiased random selection of individuals
612-428: A type of automobile airbag Other uses [ edit ] Sample Registration System, Indian demographic survey Savannah River Site , a US Department of Energy nuclear facility Selhurst railway station , London, England, National Rail station code Social Reporting Standard , a method of reporting business responsibility Stealth Recon Scout , a sniper rifle made by Desert Tech Standard RPG System ,
648-432: Is a sequential algorithm and requires knowledge of total count of items n {\displaystyle n} , which is not available in streaming scenarios. A very simple random sort algorithm was proved by Sunter in 1977. The algorithm simply assigns a random number drawn from uniform distribution ( 0 , 1 ) {\displaystyle (0,1)} as a key to each item, then sorts all items using
684-418: Is different from Wikidata All article disambiguation pages All disambiguation pages Simple random sample The principle of simple random sampling is that every set with the same number of items has the same probability of being chosen. For example, suppose N college students want to get a ticket for a basketball game, but there are only X < N tickets for them, so they decide to have
720-503: Is important so that if many samples were drawn, the average sample would accurately represent the population. However, this does not guarantee that a particular sample is a perfect representation of the population. Simple random sampling merely allows one to draw externally valid conclusions about the entire population based on the sample. The concept can be extended when the population is a geographic area. In this case, area sampling frames are relevant. Conceptually, simple random sampling
756-449: Is similar to cluster sampling, since the choice of the first unit will determine the remainder. This is no longer simple random sampling, because some combinations of 100 students have a larger selection probability than others – for instance, {3, 13, 23, ..., 993} has a 1/10 chance of selection, while {1, 2, 3, ..., 100} cannot be selected under this method. If the members of the population come in three kinds, say "blue" "red" and "black",
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#1732844201200792-435: Is the draw-by-draw algorithm where at each step we remove the item at that step from the set with equal probability and put the item in the sample. We continue until we have a sample of desired size k {\displaystyle k} . The drawback of this method is that it requires random access in the set. The selection-rejection algorithm developed by Fan et al. in 1962 requires a single pass over data; however, it
828-432: Is the simplest of the probability sampling techniques. It requires a complete sampling frame , which may not be available or feasible to construct for large populations. Even if a complete frame is available, more efficient approaches may be possible if other useful information is available about the units in the population. Advantages are that it is free of classification error, and it requires minimum previous knowledge of
864-480: Is typically done " without replacement ", i.e., one deliberately avoids choosing any member of the population more than once. Although simple random sampling can be conducted with replacement instead, this is less common and would normally be described more fully as simple random sampling with replacement . Sampling done without replacement is no longer independent, but still satisfies exchangeability , hence most results of mathematical statistics still hold. Further, for
900-407: The 6 columns at random. This would be an epsem sample but not all subsets of 5 pupils are equally likely here, as only the subsets that are arranged as a single column are eligible for selection. There are also ways of constructing multistage sampling , that are not srs, while the final sample will be epsem. For example, systematic random sampling produces a sample for which each individual unit has
936-470: The UK Medicine [ edit ] Sex reassignment surgery , now called gender-affirming surgery Silver–Russell syndrome , a growth disorder Slipping rib syndrome , a painful condition affecting the ribs Slow-reacting substance of anaphylaxis , a type of secretion Social Responsiveness Scale , a measure of autistic traits Somatostatin receptor scintigraphy , used to find carcinoid and other types of tumors Snyder–Robinson syndrome ,
972-509: The US Air Force Security Response Section , a unit of South Australia Police Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title SRS . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=SRS&oldid=1228110643 " Category : Disambiguation pages Hidden categories: Short description
1008-425: The free dictionary. SRS or SrS may stand for: Organizations and companies [ edit ] Savez Radio-Amatera Srbije , a Serbian amateur radio organization Sea Ranger Service , a social enterprise managing ocean areas Sea Research Society , for diving and underwater archaeology Serbian Radical Party ( Srpska radikalna stranka ), a political party in Serbia Signalling Record Society ,
1044-596: The inelastic scattering of photons String rewriting system , in computer science and mathematical logic Strontium sulfide (SrS), an inorganic compound Synchrotron Radiation Source , an X-ray facility in Cheshire, England Mathematics [ edit ] Simple random sample , a method of sampling in statistics Stratified random sample , a related method of sampling Software [ edit ] Sender Rewriting Scheme , an email mechanism Sequence Retrieval System , bioinformatic software by LION Bioscience AG Software requirements specification ,
1080-445: The key and selects the smallest k {\displaystyle k} items. J. Vitter in 1985 proposed reservoir sampling algorithms, which are widely used. This algorithm does not require knowledge of the size of the population n {\displaystyle n} in advance, and uses constant space. Random sampling can also be accelerated by sampling from the distribution of gaps between samples and skipping over
1116-454: The late Imperial and early Soviet periods Society for Renaissance Studies , a UK-based academic society Spanish Riding School , an Austrian equestrian institution Sperry Rail Service , a rail inspection contractor SRS Cinemas , in India SRS Labs , an American audio technology engineering company Surveillance and Response Support, a unit of the European Centre for Disease Prevention and Control Southwick Regional School ,
SRS - Misplaced Pages Continue
1152-436: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=SRS&oldid=1228110643 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages SRS [REDACTED] Look up SRS in Wiktionary,
1188-522: The number of red elements in a sample of given size will vary by sample and hence is a random variable whose distribution can be studied. That distribution depends on the numbers of red and black elements in the full population. For a simple random sample with replacement, the distribution is a binomial distribution . For a simple random sample without replacement, one obtains a hypergeometric distribution . Several efficient algorithms for simple random sampling have been developed. A naive algorithm
1224-511: The population other than the frame. Its simplicity also makes it relatively easy to interpret data collected in this manner. For these reasons, simple random sampling best suits situations where not much information is available about the population and data collection can be efficiently conducted on randomly distributed items, or where the cost of sampling is small enough to make efficiency less important than simplicity. If these conditions do not hold, stratified sampling or cluster sampling may be
1260-439: The probability ( P ) of a given person being chosen, since we know the sample size ( n ) and the population ( N ): 1. In the case that any given person can only be selected once (i.e., after selection a person is removed from the selection pool): 2. In the case that any selected person is returned to the selection pool (i.e., can be picked more than once): This means that every student in the school has in any case approximately
1296-526: The same probability of inclusion, but different sets of units have different probabilities of being selected. Samples that are epsem are self weighting , meaning that the inverse of selection probability for each sample is equal. Consider a school with 1000 students, and suppose that a researcher wants to select 100 of them for further study. All their names might be put in a bucket and then 100 names might be pulled out. Not only does each person have an equal chance of being selected, we can also easily calculate
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