“The statistics on sanity are that one out of every four Americans is suffering from some form of mental illness. Think of your three best friends. If they’re okay, then it’s you.”     Rita Mae Brown

Greetings!

Read this assignment carefully. It’s easy to miss some of the questions.

For example, c. asks what the probability of another student whose file we pull has mental health issues. Then it asks for the probability that the student has learning/school issues OR relationship issues.  Your lecture notes explain very clearly how to calculate the probability of one event OR another occurring (p(A) or p(B)). The question does not ask you to give the probability of learning/school issues and then give the probability of relationship issues. Lastly it asks for the probability that the student fits in any category except other? Do not give the probability of the file belonging to the ‘other’ category.

It is helpful to include the calculations (and/or formula) for your answers.

Finally, make sure you state why you think convenience sampling will or will not produce the same results as random sampling.

 Remember that grammar is important. Take some time because you are still getting used to the terminology and carelessness leads to inaccuracy.

This is  helpful in understanding how random and convenience sampling differ.

Difference between Simple Random Sampling and Convenience Sampling

Simple random sampling

A sampling procedure that assures that each element in the population has an equal chance of being selected is referred to as simple random sampling .

The selection bias is not possible in simple random selection.

In simple random selection the selection of units from the population does not based on easy availability it depends upon random selection.

The result can be generalize as the selection is done randomly.

http://www.nedarc.org/nedarc/collectingData/participantSelection/probabilitySampling/images/stratifiedSample.gif

Eg: An example may make this easier to understand. Imagine you want to carry out a survey of 100 voters in a small town with a population of 1,000 eligible voters. For example, we could write the names of all voters on a piece of paper, put all pieces of paper into a box and draw 100 tickets at random. You shake the box, draw a piece of paper and set it aside, shake again, draw another, set it aside, etc. until we had 100 slips of paper. These 100 form our sample. And this sample would be drawn through a simple random sampling procedure – at each draw, every name in the box had the same probability of being chosen.

Convenience Sampling

A convenience sample chooses the individuals that are easiest to reach or sampling that is done easy.

Convenience sampling does not represent the entire population so it is considered bias.

In convenience sampling, the selection of units from the population is based on easy availability and/or accessibility.

The results can not be generalize , the results are not applicable for all ,We can’t draw any meaningful conclusion from results we obtain.

http://instruct.uwo.ca/fim-lis/504/504sam.gif

Eg : If you want to choose 5 people from a class of 50. You could choose : First 5 students who. raise their hand. First 5 students in the first row. 5 tallest students .

A convenience sample is a sample where the students are selected, at the convenience of the researcher

Dr. N.

Reference

Madhuri. (2007, April 6). Difference between simple random sampling and convenience sampling.

Retrieved from: http://meetmadhu10.blogspot.com/2007/04/difference-between-simple-random.html