Sampling Technique

Sampling techniques can be done in two ways: 

1. Random sampling (probability sampling), ie random sampling is done by lottery, ordinal (a random number table), or with the computer. Random sampling technique consists of four types, namely :

• Simple Random Sampling. The main feature of this technique is that each element of the overall population has an equal opportunity to be selected. How to use the lottery, ordinal, a random number table, or computer. The advantage is that members of the sample easily and quickly obtained. The disadvantage is that sometimes do not get complete data from the population.

• Stratified Sampling Technique. This technique is used when the population is heterogeneous or consist of a multilevel groups. Determining the level based on certain characteristics. For example: according to age, education, grade / rank, and so forth. This technique would be better if it comes with the use of proportional, so that each level is represented by a comparable amount. Equipped with a stratified proportional random is called proportional stratified random sampling. The advantage of using this way is a member of more representative samples taken. The disadvantage is the introduction of more onerous on the characteristics of the population.

• Cluster sampling techniques. Also called area sampling techniques, conditional sampling, or sampling restricted. This technique is used when the population spread in some regions, provinces, districts, subdistricts, and so on. On the map area are given plots and each plots are numbered. The numbers were then drawn at random to become a member of the sample. The advantage is a technique using B can take a large population spread across various regions and in its implementation easier and cheaper compared to other techniques. While the disadvantage is the number of individuals in each of these options are not the same and there may be a resident of a berpinda area to another area without the knowledge of researchers, so that residents become members of the duplicate sample.

• Systematical sampling technique. This technique is actually a simple random sampling technique carried out ordinarily. This means that the sample members are selected based on a specific sequence. For example every multiple of 5 or 10 from a list of employees in an office. The advantage of this technique is faster and easier. While the disadvantage is sometimes less representative of the population.

2. Non-Random Sampling (Non-Probability Sampling), which is also called incidental sampling, ie not randomly sampling. Consisting of three types, namely:

• Sampling techniques Incidentally (and accidental sampling). Accidental sampling technique carried out when the election of members of the sample is carried out on people or things that happened there or encountered. The advantage of using this technique is inexpensive, quick and easy while the disadvantage is less representative.  

• Sampling Techniques Aiming (Purposive Sampling). This technique is used when sample members are selected by khusuh based on objective research. For example for the investigation of traffic rules, only those who have a driver's license or no driver's license are made members of the sample. The advantage of this technique is cheap, fast, easy, and relevant to the purpose of research.While the disadvantage is not representative for general conclusions.

• Quota Technique Sampling. This technique is used when members of the sample at a certain level of selected denganjumlah (quotas) with certain characteristics. This technique has advantages and disadvantages in common with the aim of sampling techniques.

The magnitude of the sample must be calculated based on the specific techniques that apply to the conclusion that the population can be accounted for.