STAT 301 Statistics I Fall 2009

Project Assignment

This project provides another way to demonstrate that you have learned important concepts and skills related to collecting and analyzing data to address interesting research questions. You may work with one partner on this project assignment, submitting one report with both names, provided that both of you contribute substantially to all aspects of the project.

For this project, you are to investigate a topic of your own choosing by conducting either a randomized experiment or an observational study that involves random sampling. The steps involved are to:

• Formulate a research question that can addressed by conducting such a study;
• Develop a plan for collecting data to investigate the research question;
• Collect data according to that plan;
• Conduct a descriptive analysis of the data with graphical and numerical summaries;
• Perform an inferential analysis of the data with simulation and probabilistic methods;
• Write a detailed report that describes all aspects of your investigation and summarizes its conclusions.

Some more guidelines and advice:

• Your study must involve comparing two groups.
• The response variable can be either categorical or quantitative.
• You must have at least 15 experimental/observational units in each group.
• More is better, because it gives your test more power (a better chance of detecting a difference between the groups if there really is one).
• Your experimental/observational units do not have to be human beings!
• Random assignment is usually much easier to implement than random sampling.
• If you conduct an observational study, it must involve genuine random sampling.
• You may not use gender as the explanatory variable.
• You may also collect data on a third variable (such as gender) if you’d like.
• Your report must be word-processed, with computer output integrated into the report as appropriate.
• Make sure that it’s feasible to collect the data over the next couple of weeks.
• Try to select a topic and research question that genuinely interest you.

Timeline:

• Submit a statement of your topic, research question, and detailed data collection plan (to me via email) by Fri Nov 20.
• Collect your data, enter into Minitab, submit worksheet by Mon Nov 30.
• Submit final report by Fri Dec 4 (the last week of class).

Your report will be graded on:

• Creativity of the research question
• Quality of the data collection plan and implementation
• Correctness of the analyses
• Thoroughness of the analyses
• Validity of the conclusions drawn
• Quality of the written presentation

The sections of your report should be:

I. Introduction – 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 experimental units?  How did you select the experimental units? What groups did you compare, how did you find form them (explanatory variable)? What was your response variable?  How was this variable 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 construct 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 the collecting the data?  (Note: You can never give me too much detail in this section!)  In particular, there should be enough information that someone else could replicate your study on their own based only 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.  Write several paragraphs explaining what you find in these data, with regard to your original research question. Also perform a descriptive analysis related to a third variable, if you wish  Then apply an appropriate inference technique to address the research question on your data. Indicate clearly what test procedure you are using and why it is appropriate. Determine a confidence interval as well as p-value. Include a careful interpretation of what the p-value tells you. Is the difference between the groups statistically significant?  What conclusions can you draw?  Address both the question of causation and the question of whether you believe your findings generalize to a larger population.

IV. Conclusion – Summarize the results of your study.  What did you learn about your original research question?  What else did you learn about the topic?  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 choose to investigate in the future to build on your results?

To stimulate your creative energy in thinking about possible topics, some examples of topics and research questions that have been investigated by previous students include:

• Is balsa wood more elastic after it has been immersed in water?
• Do students perform better on a memory task while listening to classical music than pop music?
• Do students express more dissatisfaction with their roommate depending on how the question is worded?
• Are people more likely to let you borrow their cell phone to make a call depending on how you are dressed?
• Do students do worse at pinning the tail on a donkey if they are spun around first?
• Does asking a stranger to watch your laptop increase the chance that they will stop a would-be thief?
• Does time to answer the door depend on whether a doorbell was rung or the door was knocked upon?
• Is a customer more likely to respond to survey questions from a store employee than from a non-employee?

You should also feel free to extend some of the research questions from studies that we have investigated in class.