| biological sampling | Denotes sampling that can be taken without jeopardy to the whole organism (e.g., for haematological or biochemical study). Because of the complexity of biological samples it is usually supposed that the source of the sample is thoroughly mixed and hence representative; this assumption is often not true e.g., in genetic studies in mosaic patients. (05 Mar 2000) |
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| random sampling | A selection of elements by a formal randomizing device for purposes of inference about a population of inference from that population in such a way that the probability of each possible outcome may be precisely specified in advance; the inferences are necessarily stochastic. (05 Mar 2000) |
| percutaneous umbilical blood sampling | See: PUBS. (12 Dec 1998) |
| chemical sampling | A sample that is obtained by whatever means is convenient and then purified of irrelevant elements before analysis; the assumption of thorough mixing is not necessary. (05 Mar 2000) |
| petrosal sinus sampling | Sampling of blood levels of the adrenocorticotropic hormone (acth) by withdrawal of blood from the inferior petrosal sinus. The inferior petrosal sinus arises from the cavernous sinus and runs to the internal jugular vein. Sampling of blood at this level is a valuable tool in the differential diagnosis of cushing disease, cushing syndrome, and other adrenocortical diseases. (12 Dec 1998) |
| chorionic villi sampling | A method for diagnosis of foetal diseases by sampling the cells of the placental chorionic villi for DNA analysis, presence of bacteria, concentration of metabolites, etc. The advantage over amniocentesis is that the procedure can be carried out in the first trimester. (12 Dec 1998) |
| chorionic villus sampling | <procedure> A procedure for obtaining a sample of chorionic villi for the purpose of genetic testing, usually performed between 9 and 12th weeks of pregnancy. Amniocentesis testing has greatly supplanted the use of this form of genetic testing. (27 Sep 1997) |
| haphazard sampling | The assembly of data in an unprescribed and undefined fashion that allows no sound scientific inferences other than establishing the existence of types. (Finding even one unicorn in such a set would establish that unicorns can exist, but no inference about their prevalence could be made from it.) Cf.: random sample. (05 Mar 2000) |
| sampling | The policy of inferring the behaviour of a whole batch by studying a fraction of it. Origin: MF essample, from L. Exemplum, taking out (05 Mar 2000) |
| sampling studies | Studies in which a number of subjects are selected from all subjects in a defined population. Conclusions based on sample results may be attributed only to the population sampled. (12 Dec 1998) |
| snowball sampling | A method whereby interview subjects for a statistical study are obtained from subjects already interviewed for that study.This technique is most often used with target populations made up of elusive or uncooperative subjects (e.g., IV drug users). Those subjects first contacted are asked to name acquaintances, who are then approached, interviewed, and asked for additional names. In this way, a sufficient number of subjects can be accumulated to give a study adequate power. (05 Mar 2000) |
| peritoneal dialysis, continuous ambulatory | Portable peritoneal dialysis using the continuous (24 hours a day, 7 days a week) presence of peritoneal dialysis solution in the peritoneal cavity except for periods of drainage and instillation of fresh solution. (12 Dec 1998) |
| mixed discrete-continuous random variable | <statistics> A random variable that may assume some values with probabilities and others with probability densities. For example, in a 35-year-old man with familial polyposis of the colon, the distribution of time until malignant disease occurs consists of a probability that he already has cancer (which would be assigned the waiting time 0), a probability density of developing it in the future and a probability that he will die of some other cause before he develops cancer. (05 Mar 2000) |
| motion therapy, continuous passive | Movement of a body part initiated and maintained by a mechanical or electrical device to restore normal range of motion to joints, muscles, or tendons after surgery, prosthesis implantation, contracture flexion, or long immobilization. (12 Dec 1998) |
| continuous | Not interrupted, having no interruption. Origin: L. Continuus (18 Nov 1997) |