Project Instructions W18
User Manual:
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STAT 217: Introduction to Statistical Concepts and Methods
California Polytechnic State University, San Luis Obispo
vskip10pt Project
Phase Points Percent
1: Team selection 2 3%
2a: Project proposal 5 8%
2b: Project proposal meeting 2 3%
2c: Project proposal revision 3 5%
3: Data collection 5 8%
4: Preliminary report 11 18%
5a: Final report 30 50%
5b: Peer evaluation 2 3%
60 100%
Seek help
If you have any questions or need any clarification at any point, please (1) come to office
hours, (2) schedule an appointment to meet with me, or (3) post on the course discussion
forum.
Work flow
Watch: Getting Started on the Project (2:06)
Download the ProjectTemplate.Rmd file from PolyLearn. Update this file for each phase of
your project submission, and submit the resulting rendered .html file to PolyLearn (not
the .Rmd file). When submitting a phase, you may simply update information for that phase
and leave the remaining sections blank. Only one student per group needs to submit a phase.
After you have collected your data - if you want to share the .Rmd file between group members,
(1) all sharing group members will need a copy of the data set saved to their computer, and
(2) you will need to change the code used to import the data set to match the location of the
data set on your computer.
Revisions
Revisions may be requested for any phase of the project. If a revision is requested you do not
need to keep the old text that you submitted - you may simply delete older work and submit
newer work.
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Writing guidelines
•Rmarkdown does not automatically indicate misspelled words like Microsoft Word does. In
order to execute a spell check in RStudio, submit F7 . Please make sure you proof-read your
writing carefully.
•Avoid using the word correlation unless you are specifically referring to the relationship be-
tween two quantitative variables. If you are not referring to two quantitative variables, you
may discuss the relationship or the association between the two variables.
•When writing a paragraph or summary, do not refer to R variable names; instead, refer to the
meaning of the variable. For example, I might have a variable in data set called prev stats
which indicates if a student has had previous experience with statistics prior to STAT 217.
–It would be incorrect to write:
The percent of students with prev stats is 35%.
–It would be correct to write:
The percent of students with previous experience in statistics is 35%.
•If you start a sentence with a number, you must spell it out.
–It would be incorrect to write:
64 people participated in the study.
–It would be correct to write:
Sixty-four people participated in the study.
•When writing, round numbers (including p-values) to an appropriate number of decimal places.
(You don’t need to worry about rounding in your R output.)
–It would be incorrect to write:
The average weight is 130.2384638 pounds.
–It would be correct to write:
The average weight is 130.2 pounds.
–An appropriate number of decimals to round a p-value is between 2 to 4 decimals. For
really small p-values you may write “the p-value is less than 0.01”, if appropriate.
•Your projects will also be evaluated on
–overall quality: coherent sentences, few grammatical mistakes, few typos, results dis-
cussed in context of research question
–overall correctness: calculating appropriate descriptive statistics, choosing correct statis-
tical methods, correct interpretation of results
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Phase 1: Team selection
•Identify 3 to 4 classmates to work with. Include their full name and e-mail address in
the project submission. If you need help finding a team, please let me know. Include this
information in your Phase 1 submission. In addition, create your group on PolyLearn by
clicking on Select groups for project in the Project content area of PolyLearn.
•Designate one team member to be the primary contact person.
–This person is responsible for facilitating communication between team members.
–This person is my primary contact in case I have questions for your team.
•Create your team contract: state three things that you think makes a group work well
together that you all agree to do.
Phase 2a: Project proposal
Watch: Example Study Design (2:16)
Watch: The Island (3:26)
•Study Design Options
Your team may choose to do either an observational or an experimental study in the real
world or on The Island. Selection one of the following four options:
1. Observational study in the real world
2. Experimental study in the real world
3. Observational study on The Island
4. Experimental study on The Island
Be sure to state in your project proposal which option your team chose.
Real world vs The Island
–In the real world, you don’t have to conduct your study on people, but of course you
may. Your observational units could be things other than people, like text books or
cows. However, if you do conduct your study on people, make sure it is an ethical
and reasonable study. Don’t ask people to do anything or answer anything that might
make them uncomfortable. It may be easier to conduct an observational study than an
experiment in the real world.
–The Island is an online environment in which you can survey fictional people. Be aware
that the islanders do mimic real people - they give birth, die, get sick, refuse to answer
your questions, and even sleep at night. It may be easier to conduct an experiment on
The Island compared to the real world. For more details about The Island, see the end
of this document.
•Research question: State a broad research question that your group would like to address.
Motivate this question as to why it interests you.
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•Comparison groups: Regardless of whether you do an observational or an experimental
study, you are required to compare two groups. State the two groups that you are comparing.
•Population: Describe your population of interest.
•Sample: Describe how you will obtain sample from the population.
–Observational studies: include a plan for you will randomly select participants from your
population.
–Experimental studies: include a plan for (1) how study participants will be identified (it is
OK if they are not randomly selected), and (2) how you will randomly assign participants
to the two experimental groups.
•Sample size: At a minimum, each team should have at least 30 participants in each of their
two groups (for a total sample size of at least 60). You may choose to collect more data than
that. State your target sample size per group.
•Variables: All teams must identify three variables related to their research question (one
explanatory variable and two response variables). You should specifically state what variables
you want to collect data on and how you will measure the variables.
1. Categorical explanatory variable - this variable defines your two comparison groups
2. Quantitative response variable - this variable represents something that you are measur-
ing to compare between your two comparison groups
3. Categorical response variable - this variable represents something that you are classifying
to compare between your two comparison groups
Be sure you state how your variables will be measured:
–For categorical variables, what values will it take on? (e.g., little/some/a lot, or on
campus/off campus)
–For quantitative variables, what are the measurement units? (e.g., If you are measuring
time, are you doing it in hours, minutes, or seconds? If you are measuring performance
on a memory task, is that measured in terms of a score or time until completion?)
•Data collection: How do you intend to collect your data? Will you be marking data on
paper, a tablet, a laptop, or an online survey? Will team members interview individuals or
will individuals read all questions themselves? Describe your data collection protocol in as
much detail as possible.
•Other protocol: There may be some other details you need to address. Any other study
details should go here.
•Predictions: Discuss what predictions you have for what you will discover. In your predic-
tions, address both:
1. the relationship between your categorical explanatory variable and your quantitative
response variable
2. the relationship between your categorical explanatory variable and your categorical re-
sponse variable
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Note: In this project, you will not examine the relationship between your quantitative re-
sponse variable and your categorical response variable.
Note: Posting a survey on a Facebook page (or other form of social media) is not an acceptable
study design.
Phase 2b: Project proposal meeting
•Select an appointment time to meet with Dr. Pileggi to discuss your project proposal. The
more group members that can attend the better, but not all group members are required to
attend.
Phase 2c: Project proposal revision
•Re-submit your project proposal according to any comments discussed with Dr. Pileggi.
•Make sure any changes you make are reflected throughout your study design. For example:
–If you change a variable that you study, that should be reflected in your research question
and in your predictions.
–If you change the way you obtain your sample, then you may need to update your Data
Collection.
Phase 3: Data collection
•Wait to do data collection until your project proposal has been approved.
•Import the data into R include the import code in an R chunk.
•Provide a summary of the data set with the command summary(mydata) in an R chunk.
•Tips:
–Store your data in a single spreadsheet.
–Your spreadsheet should have three columns for three variables:
Variable 1: categorical explanatory variable
Variable 2: quantitative response variable
Variable 3: categorical response variable
–Save your spreadsheet as a csv file to import into R(you can import other file types, but
we will primarily be using csvs throughout the quarter).
–Keep the name of your data set short (one word) so it is easy to work with.
–Keep the names of your variables short (one word) so they are easy to work with.
–Be consistent in your data entry. For example, if you are entering gender make sure
you agree that it should be entered as male and female. Otherwise, different students
may enter M,Male,male,mwhich would then require you to do data cleaning before you
analyze your data.
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Phase 4: Preliminary report
•Produce a figure to examine the distribution of your quantitative response variable.
•Produce at least one additional figure that compares your two groups.
•Calculate appropriate descriptive statistics to compare your two groups. Be sure to address
both (1) the relationship between your categorical explanatory variable and your quantitative
response variable, and (2) the relationship between your categorical explanatory variable and
your categorical response variable.
•Write brief paragraph describing your findings. This paragraph should include, at a minimum,
the sample size achieved in each group, specific statistics per group, and commentary on what
the figures show.
•Tips:
–If you need help with the R commands, please review Lab 3! You learned all of the
commands necessary to complete this phase in Lab 3.
–Please note that formal statistical tests should NOT be submitted with this phase (there
should not be a p-value or a confidence interval). This phase is only about describing
your sample data.
Phase 5a: Final Report
•Statistical methods:
1. State the statistical methods you will use to evaluate the relationship between
(a) your categorical explanatory variable and your quantitative response variable
(b) your categorical explanatory variable and your categorical response variable
2. State the conditions necessary for each statistical method in the context of your research
question (e.g., simply stating “normal” is not sufficient.)
3. Evaluate if the conditions are satisfied. If a condition has an “or” in it, evaluate both
parts of the condition even if one part is already satisfied. Comment on your findings.
Note: If your conditions are not satisfied you may discuss this in the Limitations section.
•Statistical results:
1. Execute your statistical analysis.
2. Write at least one paragraph summarizing your results in the context of your data. This
should include discussion of both the evidence and strength of association.
•Limitations: State any limitations of your study. Pay particular attention to any measure-
ment error that may have occurred, include discussion of all possible forms of bias, whether
or not you can draw cause and effect conclusions, and if any conditions for statistical inference
were violated. Justify your statements.
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•Conclusion: Discuss the overall findings of your study and how they relate to your broad
research question. Do your findings match your predictions? Suggest reasons for what you’ve
observed (e.g., why do you think these groups differ? or are not very different?). Provide
recommendations based on your analyses (recommendations may not apply to all research
questions). Discuss what you might do differently next time. What related research questions
could a future team investigate to build on your results?
•Project title: Modify the header of your Rmarkdown document to include an overall title
for your project.
•STOP! Review writing guidelines prior to submission.
Phase 6B: Peer evaluation
•All team members are expected to contribute equally to the project.
–Two points of your individual project grade comes from completing the peer evaluation
form on PolyLearn.
–After peer evaluations are assessed by the instructor, an individual’s project grade may
be adjusted by ±20% from the overall group grade.
•Here is how you will assess yourself and your peers:
Rate the individual on the following attributes according to the scale
1 = Strongly disagree, 2 = Disagree, 3 = Agree, 4 = Strongly agree
∗Communicated well with group members (electronically or in person)
∗Willingly volunteered for or accepted assigned tasks
∗Contributed positively to group discussions with useful ideas
∗Completed work on time or made alternative arrangements
∗Did work accurately and completely
∗Contributed a fair share to the project
∗Overall was a valuable member of the team
More about The Island
•All students have been added to the Island via their CalPoly email address.
•The Island has 38 villages. Each of these villages contains households of living Islanders as
well as a cemetery where users can view details of Islanders who have died in the village. The
combined population (living and dead) is 14,771 Islanders.
•To obtain information from an islander, use the map to click on the Village, and then the
town, and then the resident, then an Islander. Once a person is selected, you will see some
family information and his or her history. Click the link for “Obtain consent” to determine
whether this person is willing to participate in your study. Then you can “set a task” which
include “complete my survey” or you can impose a treatment or take a measurement. You
should also add the person to your contacts so you can follow up with them later (e.g., which
treatment group did you assign the person to?!).
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•To survey the Islanders, follow the link for Survey and then edit your survey. There are about
50 survey questions to choose from. Longer surveys take longer for the Islanders to complete
so dont ask too many questions. Also be aware that some Islanders may choose to lie on a
survey.
•You can then view the results for a contact by either clicking on the person and view task
history or in the contact list click on the results link. You have the option of collecting data
daily or every thirty seconds
•I encourage you to play around with the Island to help you formulate your research questions.
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