Bellwork August Copy and answer. Have Girls vs. Boys Handout on Desk What type of sample is each of the following? 1. If you mail a questionnaire to 100 randomly selected students at a school? Random sample 2. If you survey 20 people as they walk past you on the street. Convenience sample 3. You survey visitors to a political website in order to predict the winner of an upcoming election. Biased sample
Bellwork August Copy and answer. Have Girls vs. Boys Handout on Desk What type of sample is each of the following? 1. If you mail a questionnaire to.
Dec 28, 2015
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Bellwork August Copy and answer.
Have Girls vs. Boys Handout on Desk
What type of sample is each of the following? 1. If you mail a questionnaire to 100 randomly
selected students at a school? Random sample
2. If you survey 20 people as they walk past you on the street. Convenience sample
3. You survey visitors to a political website in order to predict the winner of an upcoming election. Biased sample
Girls vs. Boys How do populations and samples fit in with
central tendencies in the girls vs. boys lab?
Unit 1Chapter 7Section 9
Scatter Plots Pg. 416
EQ:What is the difference between positive correlation, negative correlation, and no relation in scatter plots?
What is a scatter plot? Video Clip
http://player.discoveryeducation.com/index.cfm?guidAssetId=BBC2764E-EA6D-4145-87FF-1E9FF1971509&blnFromSearch=1&productcode=USDogs
Correlation is the relationship of two or more things, parts, etc.
WRITE DOWN 1 FACT FROM THE VIDEO CLIP.
Definitions: Scatter plot: a graph with points plotted to show
a possible relationship between two sets of data
Negative correlation: two data sets have a negative correlation if one set of data values increase while the other decreases
positive correlation: two data sets have a positive correlation when their data values increases or decreases together
no correlation: two data sets have no correlation when there is no relationship between their data values
To find out if two sets of data may be related, you can make a scatter plot of the data values in each set.
A scatter plot has two number lines, called axes—one for each set of data values.
Each point on the scatter plot represents a pair of data values. These points may appear to be scattered or may cluster in the shape of a line or a curve.
CorrelationsThere are three ways to describe data displayed in a scatter plot.
Positive Correlation
The values in both data sets increase at the same time.
Negative Correlation
The values in one data set increase as the values in the other set decrease.
No Correlation
The values in both data sets show no pattern.
Practice
Steps for creating a scatter plot1. Determine the scale and interval for each
axis
2. Plot the point for each pair of values
3. Label the axes and the graph
Example 1Use the data to make a scatter plot. Describe the relationship between the data sets.
Type U.S. Only Rest of World
Mammals 63 251
Birds 78 175
Reptiles 14 64
Amphibians 10 8
Fishes 70 11
Clams 61 2
Number of Endangered Species
0 20 40 60 80
300 240
180
120 60 0
U.S.
Rest
of
Worl
d
Number of Endangered Species
There appears to be no relationship between the data sets.
1940 8,9951950 6,8581960 4,1321970 2,8811980 2,8181990 2,864
Number of farm workers in thousands
Year
Example 2
1940 1960 1980 2000
10,000
8,000
6,000
4,000
2,000
Use the data to make a scatter plot. Describe the relationship between the data sets.
Year
Num
ber
(in t
housa
nds)
Number of Farm Workers
The number of farm workers decreased from 1940 to 1970, which creates a negative correlation.
Example 3
Write positive correlation, negative correlation, or no correlation to describe each relationship. Explain.
The graph shows that as area increases, population increases. So the graph shows a positive correlation between the data sets.
Example 4Write positive correlation, negative correlation, or no correlation to describe each relationship.
Guitar String Frequency
200
300
400
500
600
700
40 60 80 100 120
Length of string (cm)
Fre
qu
en
cy
(vp
s)
The graph shows that as the length of string increases, frequency decreases. So the graph shows a negative correlation between the data sets.
vps = vibrations per second
Example 5Write positive correlation, negative correlation, or no correlation to describe each relationship. Explain.
The number of vacation days is not related to height. So there would not be any correlation between these two variables.
height and number of vacation days
Work Session- A Sport with Teeth A scatter plot shows the relationship
between 2 quantities. Look at the scatter plot on your handout. Use the scatter plot on your paper to
answer the questions. Read each question carefully. Good Luck!
Closing- Positive, Negative, or No
Correlation?
Negative Positive
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