October 5, 2006
Lizzie Dement
STATISTICS
Sample- Subset of population
Techniques that are bias:
- Mailing out Surveys (only certain people will answer them)
- Only surveying IB Students
- Threatening people who are completing Surveys
Discreet Data- Can be counted with integers
Continuous Data- Time continuous variable
Group Data- with the Data the range of variables must always be equal
Such as:
Age
0<a<5
5 < a < 10
10 < a < 15
Etc.
-Lower and upper interval boundaries (lower = 0 and upper =5)
-Interval Width = upper interval boundary – lower interval boundary
- mid-interval boundary = (lower + higher) / 2
-PAUSE FOR MUSIC(… um thanks Cary)
Range
0<a<5
5 < a < 10
10 < a < 15
Mid-interval Value
2
7
12
Number of People
10
15
12
Cannot figure out exact value but…
We do find out
(10x2 + 15x7 + 12x12) / 37
Frequency is shown in a bar graph
Frequency chart= as seen above
Other charts:
- Cumulative frequency chart
- Relative frequency chart
- Cumulative relative frequency chart
# TV
0
1
2
3
4
# Housholds
2
10
65
20
3
Relative
.02
.1
.65
.2
.03
Cummulative
2
12
77
97
100
Cumulative Relative
.02
.12
.77
.97
1.00