Introduced by R A Fisher in 1926 so that inferential statistics could be carried out to analyse differences between groups of subjects
allocation of individuals to groups, eg for experimental and control regimens, by chance, in order to make groups similar at the start of an investigation The randomisation process may or may not consider particular characteristics of the subject being entered
(Cochrane definition) Method used to generate a random allocation sequence, such as using tables of random numbers or computer-generated random sequences The method of randomisation should be distinguished from concealment of allocation because of the risk of selected bias, despite the use of randomisation, if there is not adequate allocation concealment For instance, a list of random numbers may be used to randomise participants, but, it the list is open to the individuals responsible for recruiting and allocating participants, those individuals can influence the allocation process, either knowingly or unknowingly
Procedure to ensure that every member of a target population has an equal chance of inclusion in a sample Ideally, each member of the population of interest would be assigned a number and then the sample to be used in the experiment would be randomly chosen based on these numbers This is unlikely to happen but it is good practice that once the sample is identified for testing, they are then randomly allocated to the different conditions in the experiment If for some reason your initial sample of the population of interest is biased (maybe you chose people who are particularly tolerant to alcohol), then the idea is that these individuals are equally distributed throughout your conditions and as such will not bias the group comparisons
The process of assigning trial subjects to treatment or control groups using an element of chance to determine the assignments in order to reduce bias return to contents
Randomization (in scientific experiments) provides data observations that are independently distributed, as required for the valid application of statistical methods By random allocation of experimental units and the sequence in which trials are conducted: (1) effects of extraneous factors are averaged out; (2) experimenter bias is removed The use of controls can help varify randomization
The process of selection done in a way so that there is no predictable or specific pattern In a research study, the assignment of volunteers to one test group or another is randomized to eliminate the possibility that the results will be influenced to factors not measured in the study In the MOMS the chances of being in either the prenatal or postnatal surgery groups is 50%, the same odds as getting a heads or tails when flipping a coin
A technique of assigning patients to treatment and control groups that is based only on chance distribution It is used to diminish patient selection bias in clinical trials Proper randomization of patients is an indifferent yet objective technique that tends to neutralize patient prognostic factors by spreading them evenly among treatment and control groups Randomized assignment is often based on computer-generated tables of random numbers
Assignment of subjects to different treatments, interventions or conditions according to chance rather than systematically (e g , as dictated by the standard or usual response to their condition, history, or prognosis, or according to demographic characteristics)
Ideally, a process that ensures every member of a population has an equal chance to be included in the study's sample This is often not possible Cardiologist at MUSC can not select study patients from all patients with unstable angina, only those who are admitted to MUSC More importantly, randomization means that study patients are assigned to treatment or placebo groups for the experiment, without regard to any patient characteristics or study personnel desires or biases
the arrangement of a set of objects in a random order, a set of treatments applied to a set of experimental units is said to be randomized when the treatment applied to any given unit is chosen at random from those available and not already allocated
There may be several different treatments being compared in a clinical trial; to avoid any unfair concentration on any particular treatment, patients are assigned treatments at random by a computer
allows unbiased estimates to be made of sample statistics such as the sample means Experimental units, e g animals, test-tubes etc , should be assigned to treatments at random It may also be necessary to apply treatments at random, i e not in the same sequence
A schedule for allocating treatment material and for conducting treatment combinations in a DOE such that the conditions in one run neither depend on the conditions of the previous run nor predict the conditions in the subsequent runs Note: The importance of randomization cannot be over stressed Randomization is necessary for conclusions drawn from the experiment to be correct, unambiguous and defensible
a procedure in which the assignment of subjects and treatments to groups is based on chance Randomization ensures control over the extraneous variables and increases the reliability of the experiment
The use of probability sampling to assign subjects to experimental and control groups ratio scale: A measurement of a variable that results in the classification of phenomena into a set of attributes This scale is characterized by an absolute zero point as well as equal distance between attributes research triangulation: The use of multiple methods of investigation The assumption for use of this method is that any bias inherent in the study would be neutralized in conjunction with other data sources and collection procedures There are two types