Download User Test Memorandum To: Derek Risse From: Caitlin Day Date

User Test Memorandum
To: Derek Risse
From: Caitlin Day
Date: October 9, 2016
Subject: Results of User Testing for “How to Use a TI 84 Calculator to Find the Probability Mass Function
for a Binomial Distribution”
Introduction
The instruction set that is the basis for the user test is how to use a TI 84 calculator to find the
probability mass function for a binomial distribution. This method is mainly used to find the probability
that an event will or will not occur in a given amount of “X” trials, given the “p” probability that it will
occur in “n” trials. For example, if the probability that you will get heads in 10 coin flips is 55%, what is
the probability that you will get heads every time in 6 coin flips? The target audience for this instruction
set includes students who want to find a quicker way to find their answer, or a way to check their
answer after using the longer version of the formula. It could also be for people who are new to a TI 84
and want to know how to use it for these types of calculations. To test the usefulness of the WikiHow
instruction set, a user test was completed after individuals were asked to use the instruction set. The
results of the user test mainly illustrated a need for further explanation of each step and its purpose
when going through the instruction set, and to include an example to follow along with.
Objectives
The purpose of the user test is:
1. To test the readability of the content
2. To test the ease of using the instruction set to complete the task
3. To test if the user thought the instructions help to save time
4. To test if the set was helpful
5. To collect any suggestions for improving the instruction set
Method
To begin, I sought out two users of differing levels of experience with binomial distributions and with
calculating probability mass function. My first user was my boyfriend, William Mackay, who had recently
taken probability and statistics at Wayne State University and received and A in the class. He has a solid
understanding of the purpose for finding the probability mass function. He is also a daily calculator user.
He served as my user with advanced experience in the topic. My second user was my mother, Pamela
Day, who has never taken a probability and statistics course, and has not used a TI 84 calculator before.
She served as my novice user.
Once my users were chosen, I personally asked them to participate in the test. Once they agreed, I set
them in a room individually. I provided them with my own TI 84 calculator, and with my laptop that had
the WikiHow article open on the internet, and the user test opened in a word document. I asked them
to please read the instructions on the user test first, then complete the tasks illustrated on WikiHow,
and finally to please complete the survey on the user test in the provided word document.
The user test consists of asking the user to first manually calculate the answer for a given example and
to take note of the time taken to complete the task. This can be done using either the calculator or by
hand if preferred. Then, the users are asked to follow the WikiHow instruction set and find the same
solution. They are then asked to complete a survey. The survey includes questions about the usability of
the instruction set. The survey questions consist of asking the user how well they were able to read the
WikiHow instructions, how easy it was to complete the task, if they thought the second method saved
them time, and if they thought the instructions were helpful. The last question asks them to provide any
comments or suggestions on the instruction set.
Results
After reviewing the responses to the user test, I found them to be generally positive. For the first
question, both had responded that the WikiHow instructions were “easy” to read. This is a good
response because for the instructions to be useful for all skill levels, one must be able to interpret the
instructions clearly. For the second survey question, William responded that the task was “very easy” to
complete using the WikiHow method, while Pamela said it was “easy.” Again, these are the responses
that I aimed for, since the purpose of these instructions is to make the life easier for students or
statisticians. For the third question, Pamela answered “yes” when asked if the WikiHow instruction set
method helped her save time. This is the preferred response. On the other hand, William responded he
was neutral about saved time. Based on this response, I decided to follow up with William. I asked why
he felt neutrally about saved time, and he said “I know how to manually find the probability mass
function pretty quickly already, so I wouldn’t say that this method saved me that much time, but it is a
simpler method. It saves me some time if I don’t have the formula programmed into my calculator
already.” So, it seems William is so experienced with the manual method, that it only saved him a small
amount of time. This is still a helpful review, because the goal is to save time, even if it is a small
amount. This is because when a student is time pressured, say, for a test, every second counts. For the
fourth question, both answered “yes” to the question of if they found the instruction set helpful. This is
a successful response. Finally, some suggestions were made for the fifth portion of the survey. Pamela
commented that she thinks there should have been more explanation throughout each step of the
instructions, and a better explanation of the purpose. William suggested giving an example to follow
along with. Both of these suggestions will be taken into account when revisions of the WikiHow article
are made.
Conclusion
Overall, the user test showed that the WikiHow instruction set was helpful, informational, and helps
individuals save time. It also illustrated some improvement that could be made to help users gain more
understanding for the purpose of the task. Each step will be improved to add more detail in explanation
and an example will be added to the set to follow along with each step.
Appendix
William Mackay:
Follow up with William on question 3: “I know how to manually find the probability mass function pretty
quickly already, so I wouldn’t say that this method saved me that much time, but it is a simpler method.
It saves me some time if I don’t have the formula programmed into my calculator already.”
Pamela Day: