Mean, SD, t-test
Fri, Mar 5, 2027 · Week 7 · Biotechnology for Health (Biomedical Innovations)
Today's goal: Compute the mean and standard deviation and explain the purpose of a t-test for your data.
This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.
Using my baseline heart-rate data: 72, 70, 74, 71, 73 bpm.
Mean: (72 + 70 + 74 + 71 + 73) / 5 = 360 / 5 = 72 bpm.
Standard deviation (sample):
- Deviations from mean: 0, -2, +2, -1, +1
- Squared deviations: 0, 4, 4, 1, 1 (sum = 10)
- Divide by n - 1 = 4: 10 / 4 = 2.5
- Square root: SD = about 1.6 bpm
What a t-test compares: a t-test asks whether the difference between the means of two groups (my baseline mean vs my after-activity mean) is large enough, relative to the spread in the data, that a difference this big would be unlikely if the two conditions really made no difference.
Does my data call for one? Yes. I have two conditions (rest vs activity) and I want to know if the higher activity mean is a real difference, so a two-sample t-test fits.
This model shows the level of evidence and organization needed to complete: Completes the Problem 2 descriptive-statistics practice: mean and standard deviation computed per condition with steps shown, plus a written explanation of when a t-test is used.
- Name the variables and include units.
- Enter observations without changing the raw values.
- Check labels, calculations, and patterns before interpreting the data.
Keep the structure. Replace the question, facts, measurements, and evidence. Then recheck units, vocabulary, and whether the conclusion goes beyond the evidence.
Also due today: Submit your statistics practice with calculations shown on Schoology by end of period.
Turn in: Statistics practice: mean and standard deviation calculated for each condition with steps shown, plus a written explanation of what a t-test compares and whether it applies to the data.
Go to Schoology to turn this in.
Submit one PDF. Schoology attaches your name to your upload; on the page itself, write your period and code. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf.
Open Schoology PDF upload helpIf you cannot get in, see Mr. Mendoza. Do not skip the work.
Claim ceiling: All numbers in this packet are invented instructional values, not student or patient measurements. Means and sample SD describe those numbers. No calculation proves a physiological effect, clinical importance, instrument accuracy or causation. A t-test needs a suitable design and assumptions; mean and SD alone cannot settle its result.
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.
It builds this reusable test skill: Interpreting standard deviation as a measure of data spread.
- Name the concept or data pattern being tested.
- Cross out choices that violate that rule or the evidence.
- Justify the best remaining choice before checking the answer.