Sampling Method IN Clinical Research
Abstract
Medical investigation for particular illness is carried out with specific objective, on a particular set of population in medical research. Factors involved in research affects result quality therefore, practices used for fieldwork plays critical role. Content discuss below fall through some light on various measures considered during sample collection. Appropriate utilization of information is crucial because improper use of work result in defective outcomes.
Introduction
The process which help to represent the properties and characteristics by selecting only small amount of material of a bigger sum and prepared for exploration in laboratory is defined as sampling. In medical research, the population as group with particular disease under certain conditions is taken, for example, we are performing a record on patients suffer from heart attack which will be difficult to take account of whole population under same condition all over the world and to serve each of them. Thus, the main aim is to comprise small portion of this group called test populace whereas whole population is referred as target populace. Selected one should be representative to the target population and also it should have great efficiency without errors. Method of selecting suitable testing sample from the target population is called sampling method.
Sampling method
Two mostly used sampling methods are:
Probability sampling method: The process in which the chance of every member to be selected and to provide more suitable agent which is the representation of target population.
Non- Probability Sampling Method: Non-systematic process to select the sample from population and it does not assure conistency of each element from target.
Probability Sampling Method further classified into following types: Simple Random Sampling, Stratified Sampling, Cluster (Multistage) Sampling, Systematic Sampling.
Non-Probability sampling Method is divided into: Convenience Sampling, Judgmental Sampling, Snowball Sampling, Probability Sampling.
Simple Random Sampling
In irregular sampling, researcher have list of subjects from target population and he choose the sample irregularly. For this researcher can mark number to all participants and can choose nonspecific number. In Pakistan, study performed to evaluate stroke percentage and ischemic attack which is included in Kamal et al. (7). During investigation, information was collected from different households of Pakistan related to disease condition in specific area. Then a statistical data about the predominance of stroke in certain area of Pakistan was generated. Usually through prior evaluation data is collected and made conclusion.
Stratified sampling
On basis of analytical facts such as age, sex, qualification, disease etc. the whole population to be evaluated is divided into indistinguishable subgroups. Random sample are then chosen from these subgroups. IV tissue plasminogen activator in extreme stroke is used in health center in Michagan. Deng et al. (8) performed experiment on stroke patients. Investigating all the patients in the hospital is difficult hence stratified random examining is utilized to build doctors facilities rundown. Stroke amount which is released evaluate the stratified facilities of doctor and equivalent number of health center which comes under every subgroup were haphazardly picked. The satisfying current practice is assured by stratified sampling because of this.
Systematic sampling
Systematic frame is not required to study target populace in this method. Non- systematic group is selected directly according to standardized rule, a fixed gap of subject is determined.
Cluster sampling
In this method, large population is covered so it is divided into subgroup as a cluster. Then, outline by specialist is drawn. Final sample are taken from the bunch which is precise as simple random sampling. In this method, the process is done with two phases. Firstly, eligible clusters are picked out and then individual are selected from that cluster that is why this technique is called multistage.
Convenience Sampling
In clinical research, convenience sampling is relevant and widely employ despite being non-probability testing strategy. The researcher select based on the access of sample. Due to sampler conveniency, this method is very fast and cheap. For instance, research on people with HIV (Human Immunodeficiency virus) in medical center of specific area are done by choosing the people who are available and approachable at the time of sampling and carry out the further investigation.
Judgmental sampling
Specialist decides to pick subjects through this technique on their own. A particular characteristics is followed, researcher expect it to be reasonable to speak with population. Probability of bias is high therefore, this technique is criticized generally.
Snowball sampling
When population cannot be situated in certain place and hard to reach them, subsequently snowball sampling is utilized. We can take example of study on street children, researcher have difficulty to be in touch with all of partners from same member hence, he contact one peer and gather all the required information.
Chain Of custody
It is the process which keep evidence of each and every step carried during analysis such as care of sample, control used, transportation and handling of test sample, even method of examination and sample disposal proof.
Purpose of chain of custody
Generally, chain of custody is send along with the test for-Scene information: In order to have knowledge of sample content in the particular area and their surrounding area.
Sample location
It should be mentioned in detail so as to track down the sample and to know their condition.
Quality control assessment
This is done to verify that the quality control is put into action and properly maintained.
Methods Assurance
To check the correct sampling procedure and assure it whether it is correct.
Legal Integrity
Preserve the trial virtue and present it in court whenever required.
Conclusion
To sum up, appropriate sampling is necessary as it has influence over the result of evaluation. Many things has to be considered and effective procedure as needed to be followed. In our opinion, stratified sampling technique is efficient one because it has wider precision, easily usable and portray the big population exactly. This process also saves time and cost.
References:
- Deng Y, Reeves M, Jacobs B, Birbeck L, Kothari R. IV tissue plasminogen activator use in acute stroke. Neurology. (2006); 66:306–12. [PubMed] Retrieved on September 27, 2018
- F. Gravetter, L. Forzano. Selecting Research Participants .Res Methods Behav Sci. (2012): 125-139 Retrieved on September 28, 2018
- Kamal A, Itrat A, Murtaza M, Khan M, Rasheed A. The Burden of stroke and TIA in Pakistan. BMC Neurol. (2009); 9:58: [PMC free article] [PubMed] Retrieved on September 28, 2018
