Take-home Midterm - Statistics 158, Fall 2023
Take-home Midterm - Statistics 158, Fall 2023
Due Saturday October 14, 12:00 PM PDT
1 Overall Guidelines
You are allowed to use textbooks, R documentation, notes, scientific papers, and other written materials in print or online to help you complete this assignment (note that you must give written attribution when using information from such a source). However, you must not consult any other person about any aspect of your project. If you have clarification or logistical questions about the assignment instructions below or about submission, you may contact Prof. Pimentel and the course staff by private bCourses message. The course staff will not answer content-related questions.
You will have 72 hours to complete the assignment. However, the assignment itself should require only a very small fraction of that time to complete. As a result, we do not plan to give extensions, and you should budget your time carefully in accordance with this policy, especially if you have other assignments or other unavoidable conflicts during the period of the midterm.
2 Experimental context
Employers wish to design workplace environments and employee interactions in such a way that employees are motivated to excel in work-related tasks. One approach is to encourage employees to consciously set and pursue goals for their own productivity. However, there is also substantial evidence from past studies in psychology that subtle “priming” factors can substantially influence human behavior even when the human subject is not consciously aware of the change. For example, in one study people who were shown a picture of a library on a computer screen subsequently spoke more softly than those who did not see the picture. There is debate within psychology about the relative importance of conscious and unconscious factors in determining a person’s motivation to complete a task.
We now consider a study1 that aims to quantify and compare the effects of conscious and non-conscious goals in a workplace. In the study, which uses a balanced and completely randomized factorial design, 96 workers in a call center were tasked with making phone calls to solicit donations for a university. At the beginnning of the shift, employees were given an information packet containing the same written information about the university. However, to investigate unconscious motivation arising from priming, one third of employees received packets containing a clearly printed color photo of a woman winning a race on the backdrop of the page, another third of employees instead received packets with a collage of achievement-related photos printed near the top of the page, and the final third received packets printed with no accompanying images (an example page from the first type of packet is shown at the end of this document). In addition, to investigate conscious goal-setting, half of employees were given a specific goal of $1200 to raise during their shift, while the other half were simply urged to do their best to raise as much money as possible. At the end of the three-hour shift, the number of dollars raised by each employee was recorded. The data is provided in the file motivation.csv available under Data on bCourses.
3 Tasks
1. (15 points) Describe in detail the units, conditions, and response for this experiment. Describe the form of the potential outcomes and report how many potential outcomes there are (as a function of the total number of subjects in the study N). Comment on the reliability and validity of the response.
2. (7 points) Imagine you were tasked with carrying out this experiment or training others to do so. Provide a detailed step-by-step procedure for how you would randomize units to treatments, and comment on any other steps you would take to eliminate possible confounding factors.
3. (15 points) Conduct an exploratory/informal analysis of the data. Comment on any major patterns you observe in the data and on the potential presence or absence of interactions.
4. (35 points) Conduct and report inferences for all the structural factors in the experiment using ran domization inference. In addition, describe three contrasts that you judge to be potentially interesting (explain why), estimate them, and conduct inference for them. At least one of these contrasts should not be a pairwise contrast. Address multiple testing for the contrasts and explain why the approach you chose is appropriate.
5. (5 points) Summarize your findings and explain the strengths and weaknesses of the study’s design. In particular, articulate in what way these finding are more trustworthy than similar findings from a purely observational study.
6. (18 points) Imagine a second version of this same study is being planned. Describe how you could use blocking to improve the design and how exactly the resulting design might be better. Be specific about the blocking factor(s) you would recommend using and why. Provide a detailed step-by-step procedure for how you would randomize units to treatments in the proposed block design.
In addition, your work will be evaluated overall for quality of writing (5 points). This includes clarity, concision, level of detail, and observance of the submission requirements below.
4 Submission
2023-10-13