Wednesday, May 5, 2010

Questions on Sampling 11-20

1. Define Non probability Sampling
The difference between non probability and probability sampling is that non probability sampling does not involve random selection and probability sampling does. It can be divided into two broad types: accidental or purpose. In purposive sampling, we sample with a purpose in mind

2. Define various non probability sampling methods
Modal Instance Sampling
Expert Sampling
Quota Sampling
Non proportional Quota Sampling
Heterogeneity Sampling
Snowball Sampling

3. Define Modal Instance Sampling
In statistics, the mode is the most frequently occurring value in a distribution. In sampling, when we do a modal instance sample, we are sampling the most frequent case, or the "typical" case.

4. Define Expert Sampling
Expert sampling involves the assembling of a sample of persons with known or demonstrable experience and expertise in some area. Often, such a sample is done under the auspices of a "panel of experts. It would be the best way to elicit the views of persons who have specific expertise

5. Define Quota Sampling
In quota sampling, you select people non randomly according to some fixed quota. There are two types of quota sampling: proportional and non proportional. In proportional quota sampling you want to represent the major characteristics of the population by sampling a proportional amount of each

6. Define Non proportional Quota Sampling
Non proportional quota sampling is a bit less restrictive. In this method, you specify the minimum number of sampled units you want in each category. here, you're not concerned with having numbers that match the proportions in the population.

7. Define Heterogeneity Sampling 
The sample for heterogeneity when we want to include all opinions or views, and we aren't concerned about representing these views proportionately. Another term for this is sampling for diversity.

8. Define Snowball Sampling
In snowball sampling, you begin by identifying someone who meets the criteria for inclusion in your study. You then ask them to recommend others who they may know who also meet the criteria. Snowball sampling is especially useful when you are trying to reach populations that are inaccessible or hard to find.

9. Define Accidental Sampling
Its just a means of convenience that this sample is being selected. Based on availability an no specific purpose or thought process is involved in this sampling.

10. What are the other synomnys of accidental sampling
Its also known as Haphazard or Convenience sampling