1. Starting out with Statistics

2. What do we do with statistics?
Describe a group using numbers
Descriptive Statistics
Infer about how a larger group of data would behave based on a smaller subset.
Inferential Statistics
A set of rules that help us make a decision about how good an inference we can make.

3. Some terms to start off Population: Sample:
All the data points that could be considered
Sample:
The data points that are being evaluated
Usually less than the population (a subset of the population)
Often a good representation of the population

4. Some terms to start off Variable Dependent variable:
A particular piece of information that can take on different values across the data that is being evaluated.
Dependent variable:
Typically what the investigator is interested in measuring
Independent variable:
Typically the way in which the data is grouped, or what is being manipulated.

5. Frequency Table A column for the variable A column for frequency
(test scores)
A column for frequency
(number of subjects who received a particular score)

6. grades 30 3
29.5 5 29
28.5 2 28 10
27.5 27 6
26.5 26 25
24.5 24 4
23.5 1 23
22.5 22
21.5 21 20

7. Frequency Table Cummulative frequency
Number of subjects who have a particular score or any that are lower (or higher)

8. grades 30 3
29.5 5 29
28.5 2 28 10
27.5 27 6
26.5 26 25
24.5 24 4
23.5 1 23
22.5 22
21.5 21 20

9. grades 30 3
29.5 5 29
28.5 2 28 10
27.5 27 6
26.5 26 25
24.5 24 4
23.5 1 23
22.5 22
21.5 21 20

10. grades 30 3
29.5 5 29
28.5 2 28 10
27.5 27 6
26.5 26 25
24.5 24 4
23.5 1 23
22.5 22 7
21.5 21 20

11. grades 30 3 73
29.5 5 70 29 65
28.5 2 60 28 10 58
27.5 48 27 6 43
26.5 37 26 32 25
24.5 24 4 21
23.5 1 17 23 16
22.5 11 22 7
21.5 20

13. grades 30 3 73
29.5 5 70 29 65
28.5 2 60 28 10 58
27.5 48 27 6 43
26.5 37 26 32 25
24.5 24 4 21
23.5 1 17 23 16
22.5 11 22 7
21.5 20

14. If you wanted to find what would you do?

15. grades 30 3
29.5 5 29
28.5 2 28 10
27.5 27 6
26.5 26 25
24.5 24 4
23.5 1 23
22.5 22
21.5 21 20

17. grades 30 3 90
29.5 5 29
28.5 2 28 10
27.5 27 6
26.5 26 25
24.5 24 4
23.5 1 23
22.5 22
21.5 21 20

18. grades 30 3 90
29.5 5
147.5 29
28.5 2 28 10
27.5 27 6
26.5 26 25
24.5 24 4
23.5 1 23
22.5 22
21.5 21 20

19. grades 30 3 90
29.5 5
147.5 29
145
28.5 2 57 28 10
280
27.5
137.5 27 6
162
26.5
132.5 26
156 25 50
24.5
73.5 24 4 96
23.5 1 23
115
22.5 22
21.5 43 21 20 60

21. ƒ
Test scores

24. Symmetric Distribution:
A distribution in which the left and right halves are mirror images.

25. Frequency
how many
Scores

26. Symmetric
frequency
scores

27. Skewed Distribution:
The majority of the scores in the distribution fall to one end. At the opposite end of the distribution is a tail.

28. frequency
scores

29. frequency
scores