[Slide 1] How can you determine whether to conduct a sample survey, an experiment, or an observational study? In this lesson you will learn why and when to conduct a sample survey, an experiment, and an observational study by considering the purpose, some advantages, and some disadvantages of conducting them. So, let’s get started.
[Slide 2] There are three main types of research, Surveys, Experiments, and Observational Studies. In a survey, individuals know they are being studied. You are asking questions of respondents. In an Experiment, Investigators apply treatments to people, animals or objects, and observe the effects of the treatments on the experimental units. I recently took place in an experiment where I was asked to apply a lotion to an affected area of my skin to see if the lotion would help heal the skin. Experiments are not always bad, and are medically necessary to determine side effects of a drug that may be presented to market. In an Observational study, the researcher simply observes the subjects and measures variables of interest without assigning treatments to the subjects.
[Slide 3] It can sometimes be hard to determine which type of research method you should use. We are now going to look at the advantages and disadvantages of each type of research. The advantages of a survey are that they are efficient and can be given in a variety of ways. Often your teacher will survey you for understanding by a simple hand raise. Have you ever received a survey in the mail? Frequently during election season Marketing Firms are hired to survey people of voting age to see what their political opinions are in order to help predict which candidate is going to win the election. The disadvantages of this type of research are that is is very dependent on honesty and motivation. It can be flawed by non response, and is open to interpretation of the person answering the questions.
[Slide 4] Experiments can establish causation. We can say with certainty that one thing causes or does not cause another when the research is not flawed. However, this type of research can be costly, or even unethical. An experiment can also be flawed by the individuals view of the researcher.
[Slide 5] An observational study can be inexpensive, and help the observer gain first hand information, and a deeper understanding of a process. The drawbacks of an observational study is that they can be flawed by the observers opinion of those being researched, and that just by observing something you cannot determine causation. It may also be unethical to perform an observational study. Like setting up a camera in the bathroom where people expect to have privacy to determine how many people wash their hands after taking care of business.
[Slide 6] Let’s take a closer look at the difference between an experiment and an observational study. If we wanted to look at the effects of smoking on lung capacity of women in an experiment we would find 100 women age 20 who do not currently smoke. We would then randomly assign 50 of them to start smoking a pack a day. After a set amount of time, say 10 years we would then measure the lung capacity of all 100 participants. This doesn’t seem to ethical does it? In an Observational study, we would find 100 women 50 of which have been smoking a pack a day for 10 years, and then measure the lung capacity of all 100 women. Notice in the observational study we did not require our participants to change anything about their current lifestyle, while in an experiment the participants were required to change something.
[Slide 7] In this lesson we discussed the types of research, Survey’s Experiments, and Observational studies and we discussed the advantages and disadvantages of each.