Purpose:
Assignments in the Lab sections requires students to perform basic statistical analyses on data collected during lab activities. While these concepts are covered in prerequisite classes, this introductory assignment gives students a chance to review commonly used stats and demonstrate that you understand these concepts.
Instructions:
- Review slides provided in Canvas on stats & scientific method
- Watch the videos below:
- What is a t-test?: https://www.youtube.com/watch?v=0Pd3dc1GcHc&t=30s
- Use the information in the videos to answer the questions below. Simply type your answer in the box below each question (the box should expand to fit your response). Note: Answers can be simple! Just a couple of sentences to demonstrate that you understand the concept.
- If you choose to use Google, etc. to complete this assignment be prepared that your answers may be incorrect and very obviously incorrect if you do not vet the source and attempt to understand the concepts.
- When you are finished, upload this file in the assignment link by the due date.
Questions
- What are descriptive statistics? Provide some examples.
- What is a t-test used for? Provide a general explanation in your own words.
- Write a simple example scenario in which the data collected should be analyzed using an independent samples t-test (unpaired t-test).
- Describe how to alter the example scenario above so that it would be appropriate to analyze the data using a paired t-test.
- What are the important pieces of information to report when writing up the result of a t-test? What does the p-value signify? What are the typical thresholds for a significant or non-significant finding?
- What does a correlation measure? Write a simple example scenario in which the data collected should be analyzed using correlation.
- What does r signify? What is represented by the negative (-) or positive (+) sign before the r value? What are typical thresholds for the r value associated with strong, medium, or weak correlations?
- Use a t-test to analyze Scenario A and complete Table A:
Scenario A: A teacher read a study stating that physical education helps kindergarten age children perform better in school overall. She questioned whether including PE would result in significantly better grades. To study the question, she compared the mean trimester grades in five schools that include PE in the kindergarten curriculum and another five schools that did not include PE. The results were as follows:
PE included: 82%, 82%, 84%, 88%, and 81%.
No PE: 78%, 75%, 95%, 72%, and 78%
Table A
| Type of t-test (i.e. paired or unpaired groups) | |
| What is the difference between the two group means | |
| Specify the calculated p-value | |
| What is the answer to the teacher’s question? Answer relative to the question as if you are reporting to someone that does not know or understand statistics | |
| List steps taken to calculate p-value in Excel and how determined answer to above question |
- Use correlation to analyze Scenario B and complete Table B.
Scenario B: The teacher examined the grades of students in her own class. She questioned whether there was a significant correlation between students’ PE scores and their grades in her class. The data was as follows:
Student PE Score Overall grade
1 15 85
2 8 70
3 16 93
4 21 97
5 10 74
6 17 75
7 15 81
8 13 73
9 15 79
10 19 88
Table B
| Specify the calculated r for this scenario (hint: r equals the square-root of R-squared) | |
| Interpret the meaning of the r value (hint: direction and strength of the relationship) | |
| What is the answer to the teacher’s second question? Answer relative to the question as if you are reporting to someone that does not know or understand statistics | |
| List steps taken to calculate r-value in Excel and how determined answer to above question |
