3.3 COLLECT & ORGANIZE DATA
Jan 29, 2016
3.3 COLLECT & ORGANIZE DATA
GATHERING DATA It’s important to gather accurate data and
to ensure the data is as complete as possible If you gather the data yourself, it is Primary
Data If you use data collected by others, it is
Secondary Data Might be errors in the published secondary
data Results might not state how data was
gathered, or limitations of the use of the data
“PRACTICE MAKES PERFECT”Come as close as you can to the centre of the circle by writing numbers for each attempt:
Attempt
Distance from Centre (cm)
1
2
3
4
5
“PRACTICE MAKES PERFECT” Let’s create a scatter plot from our data
to see if “practice makes perfect”
Dis
tance
fro
m
centr
e
Number of Attempts
Attempt
Distance from Centre (cm)
1
2
3
4
5
“PRACTICE MAKES PERFECT” Positive or negative correlation or
neither?
“PRACTICE MAKES PERFECT”
You would theoretically get a negative correlation
In other words, your first attempt would be at a large distance from the centre, and your subsequent attempts would result in the distances getting smaller and smallerer
ANALYZING DATA USING A SCATTER PLOTDavis conducted an experiment comparing a person’s leg length and how long it takes the same person to walk 100m. He gathered these data showing (leg length in cm, time taken in s).
(80,66), (73,74), (60,83), (64,62), (63,75), (78,76), (83,64), (54,81), (71,70), (78,76).a) Graph the data.b) Does the graph suggest a relationship
between leg length and time taken to walk 100m? If so, describe the relationship.
100M WALKING EXPERIMENT
50 55 60 65 70 75 80 850
10
20
30
40
50
60
70
80
90
Walking 100m
Distance (m)
Tim
e (
s)
a) Graph the data.
100M WALKING EXPERIMENT
50 55 60 65 70 75 80 850
10
20
30
40
50
60
70
80
90
Walking 100m
Distance (m)
Tim
e (
s)
b) Does the graph suggest a relationship between leg length and time taken to walk 100m? If so, describe the relationship.
>The points go down to the right. This suggests a negative
correlation.>Time taken to
walk 100m decreases as leg length increases
100M WALKING EXPERIMENT
50 55 60 65 70 75 80 850
10
20
30
40
50
60
70
80
90
Walking 100m
Distance (m)
Tim
e (
s)
>A point with first coordinate 85 might have a
second coordinate of 63.>So, someone with leg length
85cm might take about 63s to walk 100m.
c) Use the scatter plot to estimate the time it would take a person with leg length 85cm to walk 100m. Explain.
100M WALKING EXPERIMENT
More data would make Davis’ results more reliable. He could
recruit people with a wider range of leg lengths while keeping other factors, such as age, gender, and
body type, very similar.
d) How might Davis make the results of his experiment more reliable?
3.3 HOMEWORK p. 165 #1, 2, 3, 4