Stat 150
Project 2: Designing and Analyzing a Comparison Study
Goal: To investigate a research question involving a comparison of two groups by developing the question, designing a plan for collecting data to investigate that question, collecting the data according to the plan, analyzing the resulting data, and reporting the results.
Guidelines: Your study must involve either random sampling or random assignment (or both). It can be either an observational study or a controlled experiment. You are not allowed to use gender as one of your variables. The response variable can be either quantitative or categorical. Your study must obtain at least 15 observational/experimental units in each group, but you should try to obtain more if that is feasible for your study.
Keep in mind that random assignment is often easier to implement than random sampling, so we encourage you to design and conduct an experiment. If you instead opt for random sampling, keep in mind that inanimate objects are often easier to sample than human beings. Make sure to choose a topic for which it is feasible to collect data over the next several days.
You will work with a randomly assigned partner. Your partner must not be the same as for the gapminder project. This project will culminate with both an oral presentation and a written report.
Plan: During today’s class you should brainstorm possible project topics with each other, try to settle on one research question, and start to make plans for collecting the data. You should send a clear statement of your research question, along with a description of your plan for collecting data, to both instructors via email by noon on Monday. You should also make plans for when you will meet with your partner to collect the data. Please do not begin to collect the data until you receive approval for your research question and data collection plan.
To help generate your brainstorming ideas, here are some project topics that have been investigated by previous students:
Timeline:
Oral Presentation
Guidelines: Your oral presentation on Monday, November 2 should take
between 4 and 5 minutes. All members of
the team must contribute to the oral presentation. Make sure that your presentation follows the
same structure as the written report.
You should prepare visual aids to be projected to the rest of the class
(hard copies are fine). Do not just use copies of passages
from your written report as your visual aids, but they should stand alone and
be attractive, yet succinct and informative.
Feel free to be creative and to involve audience members in your
presentation.
Written Report Guidelines: Your report must be word-processed and written collaboratively by both team members. Your report should be written as to other student researchers. It should organized around (and use the headings of) the following sections:
I. Introduction – Describe your research question. Why did you choose this topic? What did you expect to find? Have similar studies been done elsewhere? Why should the reader be interested in your results and continue reading?
II. Summary of Data Collection Methods – How did you collect the data? What were the observational/experimental units? What groups did you compare; how did you find them/form them? Was it an observational study or an experiment? What was your response variable? How were the explanatory and response variables measured? What additional “controls” did you exert on the study? (E.g., did you only observe people writing or did you take any behavior such as throwing a football as indication of handedness?) Did you need to decide on any “operational definitions”? (E.g., did you pre-test any of the questions on a test group to see if the wording was clear?) Did you have any problems with non-response or other unexpected results? Did anything go wrong during the course of collecting the data? [Note: You can never give us too much detail in this section. In particular, there should be enough information that someone else could replicate your study on their own based on your description (and hopefully improve upon it based on your suggestions below).]
III. Analysis of Results – Include appropriate numerical and graphical summaries of your data. (Remember that with a categorical response, an appropriate graph would be a segmented bar graph, and relevant numerical summaries would be conditional proportions. With a quantitative response, consider dotplots and histograms, means and medians, standard deviations and IQRs.) Write several paragraphs explaining what you find in these data. Then report the p-value of your study, based on your instructors’ advice about how to calculate it. Include a careful interpretation of what this p-value tells you and the reasoning process behind your conclusion. Is the difference between the groups statistically significant? What conclusions can you draw? Be sure to refer back to the type of study conducted in explaining the scope of your conclusions. Address both the question of causation and the question of whether your findings generalize to a larger population. [Note: All computer output should be included in the body of the report. Make sure all figures and graphs are clearly labeled.]
IV. Conclusion – Summarize the results of your study. What did you learn? Did the data behave as you expected? Critique the methods used to collect the data. Is there anything you would do differently next time? How might this affect the conclusions of the study? What similar questions might someone chose to investigate in the future to build on your results?
Submitting your final report: Please submit both a hard copy (printed out) and email us an electronic copy of your final report and a Minitab file containing your data.