A1258150179YEdQP

1
????????

• ????????
• ?????????
• ??????????????
• ?????????

2
BiostatisticsFor the Biological and Health
Science

• Chapter 2
• Describing, Exploring, and Comparing Data

3
Chapter Problem

• Are nonsmoking people really affected by others
  who are smoking cigarettes, or is the effect of
  sceondhand smoke a myth?
• We will learn techniques for describing,
  exploring, and comparing data sets such as the
  three groups of data (Table 2-1).
• Descriptive statistics vs. Inferential statistics
  (use sample data to make generalizations)

4
(No Transcript)
5
2-1 Overview

• Basic tools for measuring and describing
  different characteristics of a set of data.
• Important characteristics of data (CVDOT)
• Center
• Variation
• Distribution
• Outliers
• Time

6
2-2 Frequency Distributions
7
(No Transcript)
8
(No Transcript)
9
Relative Frequency Distribution
10
Relative Frequency Distribution
11
Cumulative Frequency Distribution
12
Interpreting Frequency Distribution

• Why the last digits are all even numbers? Data
  collection

Perhaps they were counted for 30 seconds and the
values were then doubled.
13
Exploring Data
But we would not see the fundamental difference
between heights of men and women.
14
Comparing Data Sets
15
2-3 Visualizing Data

• The main objective of this chapter is to learn
  basic techniques for investigating the important
  of data sets center, variation, distribution,
  outliers, and changes over time (CVDOT).

16
Interpreting a Histogram
17
Ogive oh-jive
18
Dotplots
19
Stem-and-Leaf Plots
20
Depicting Qualitative Data
arranged in order according to frequencies
21
Scatter Diagrams
22
Time-Series Graph
23
Other Graphs
Florence Nightingale used it to convince British
officials that military hospitals needed to
improve sanitary conditions.
24
2-4 Measures of Center
25
(No Transcript)
26
Mean
(Sample size)
27
Median (???)
28
Mode (??)
29
Midrange
30
(No Transcript)
31
(No Transcript)
32
Weighted Mean (?????)
33
Skewness (??)
34
The Best Measure of Center
35
(No Transcript)
36
2-5 Measures of Variation

• One of the most important sections in the entire
  book

37
Range
38
Standard Deviation (???) of a Sample
39
(No Transcript)
40
Standard Deviation of a Population
41
Variance (???) of a Sample and Population
42
(No Transcript)
43
(No Transcript)
44
Comparing Variation in Different Populations
45
N99(?)µ77.3(?)s14.4(?)
46
Interpreting and Understanding Standard Deviation
???????
47
(No Transcript)
48
(No Transcript)
49
(No Transcript)
50
2-6 Measures of Relative Standing
51
z Scores and Unusual Values
52
Quartiles (????)
arranged in an increasing order
53
Percentiles (????)
54
(No Transcript)
55
P.72 Example
56
2-7 Exploratory Data Analysis (EDA)
57
Outliers (???)
58
Boxplots (??)

• useful for revealing the center of the data, the
  spread of the data, the distribution of the data,
  and the presence of outliers

59
(No Transcript)
60
(No Transcript)
61
(No Transcript)
62
Exercises

• ?????????,
• ?????????