1- What is the difference between non-probability and probability sampling? Give examples of both.
Probability sampling is when every element of a population has an equal chance of being selected in a particular research or survey. The sample that will be taken is purely based on chance and each unit in the population has a known nonzero probability of being chosen . An example of probability sampling is when one is doing a research on the study habits of students in a Math class of 200 students. If the intended sample size is 50 students, what one does is to write the names of each student in a strip of paper and simply pulls out 50 strips of paper to get the students to be included in the study. In non-probability sampling, the elements are selected based on certain criteria; thus, it is not based on chance. Usually, there is some personal bias that exists in this type of sampling. In the example given above, if one is to use non-probability sampling, one can get the 50 students by choosing the top 25 students and the bottom 25 students in terms of academic performance. 2- Explain the 3 purposes are research? The first purpose of research is for exploration. This research is conducted to find out more information and to gain a better understanding about a new topic. The second purpose of research is description. In this type of research, the researcher writes down his observation of events and situations. Descriptive research answers the questions what, when, where, and how.
The third purpose of research is explanation which unlike descriptive research, answers the question why. It seeks to explain things or situations.3- What are the units of analysis in a study? Name 2 of the 5 types. The units of analysis in a study can be individuals or a social artifact such as a painting or a book. 4-What is the difference between cross sectional and longitudinal research?
A cross sectional research is an observational research where the study environment is not manipulated. It compares different variables at a single moment in time. On the other hand, longitudinal research is an observation research which is conducted by observing the subjects over a period of time. Like cross sectional research, the environment is not manipulated. Longitudinal research allows the researcher to record the changes on the subjects during the time frame being observed.
Crossman, Ashley. "The purposes of research." 2013. sociology.about.com. 7 April 2013
—. "Units of analysis." 2013. sociology.about.com. 7 April 2013
Emathzone.com. "Probability and nonprobability sampling." 2013. emathzone.com. 7 April 2013