# lecture4 - Psych 100A Winter 2010 Lecture 4 Descriptive...

This preview shows pages 1–6. Sign up to view the full content.

Psych 100A Winter 2010 Lecture 4: Descriptive Statistics: Numerical summaries of data: 1.Measures of variation (cont.) 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Comments on measures of variation Range & IQR : Cannot be combined from several groups into an overall measure. Variance : Formula for the population variance 2 of a finite population, size N  1 2 2 x N i   Computation formula for s . 2 2 n 1 1 s 2
Example A study of the type of sediment found at a deep-sea drilling site showed the following percentages of cement (carbonate) material in core mples: samples: 10, 21, 12, 12, 20, 13, 24, 36, 31, 18, 17, 16, 49. ind the mode mean median range Find the mode, mean, median, range, IQR and SD of these 13 measurements. 3

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
List 10, 21, 12, 12, 20, 13, 24, 36, 31, 18, 17, 16, 49. Ordered list 10, 12, 12, 13, 16, 17, 18, 20, 21, 24, 31, 36, 49. a. Mode = 12 b. Mean = 279/13 = 21.5 c. Median = [(13+1)/2] th obs = 7 th obs = 18 4
0 21 12 12 20 13 24 36 31 18 17 16 49 List 10, 21, 12, 12, 20, 13, 24, 36, 31, 18, 17, 16, 49. Ordered list 10, 12, 12, 13, 16, 17, 18, 20, 21, 24, 31, 36, 49.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 13

lecture4 - Psych 100A Winter 2010 Lecture 4 Descriptive...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online