A statistical study is a four-step process that starts by asking the relevant questions that can be answered with the help of data. The steps include collecting, organizing, and deriving conclusions from the data.
Observational Studies
An observational study is one in which a researcher collects data from a group of people and uses it to learn more about them. Apart from the measurement of their responses, the people being observed are not affected in any way.
Sample Survey
A sample survey is one that is conducted with a group of people selected to represent a larger population. A survey is a method of gathering information about a group of people by having some of them answer questions. Completing a form, completing an online questionnaire, participating in a personal interview, or answering questions over the phone are all examples of survey methods.
Experiments
An experiment differs from an observational study in that a researcher applies different treatments to different groups and then compares the groups to see if there is any difference in a particular variable of interest. Researchers can use a well-designed experiment to see if different treatments produce different results.
Example
While studying, many students listen to music. Is listening to music beneficial to learning? This question is investigated by students in a statistics class. They come up with more specific research questions about music and learning. Following that, they create the following three studies:
Study 1
Specific research questions include:
Do most college students listen to music while studying? Do most college students believe that listening to music helps them learn better?
The statistics students conduct a survey in their other classes to investigate these questions. They enquire about the following:
Do you study while listening to music?
Do you believe that listening to music helps you concentrate and remember things better?
This is an observational study that aims to answer two questions about a college student population. Each question makes a claim about the college student population. You can use the data from this study to determine whether or not these claims are correct. However, the findings of this study do not support a cause-and-effect relationship between listening to music while studying and improved learning.
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Study 2
Specific research question: Which group of students gives higher ratings for understanding what they studied when compared to students who study in a quiet environment?
The instructor divides the class into two groups to investigate this question: (1) those who study while listening to music, and (2) those who do not study while listening to music. For a week, the students keep a journal. They keep track of the following information each time they study:
Study session duration (in minutes)
On a scale of 1–10, rate how well they understood what they studied: 1 = no comprehension, 10 = complete comprehension.
This is also an observational experiment. It compares two groups of students: (1) those who listen to music while studying and (2) those who do not listen to music while studying. This can also be viewed as an observational study of a single population (college students) that looks into the relationship between two variables: listening to music while studying and perceived comprehension of the material studied.
Study 3
Is it true that listening to music improves students' ability to recognize information quickly?
The instructor uses word-search puzzles to investigate this question. She separates the students into two groups. On one side of the room, students work on a 3-minute word puzzle while listening to music on an iPod. On the other side of the room, students work on a three-minute word puzzle without music. The average number of words found by each group is calculated by the instructor.
This research is a test. The instructor plays with music to see how it affects puzzle completion. The findings of this study may show a cause-and-effect relationship between listening to music while studying and learning gains. However, the ability to quickly identify information, such as words in a puzzle, is a more narrowly defined improvement in learning.
Conclusion
In this tutorial on the Types of Statistical Studies, you learned about the various methods of collecting and analyzing data to arrive at a conclusion. You answer a question about a population by selecting a sample and conducting an observational study.
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