Basic HTML Version
Q
uantitative
R
easoning &
P
roblem
S
olving
152
© 2014 Pacific Crest
Using the
Sample Planning Wizard Demo,
complete columns (b), and (c) and then calculate columns
(d) and (e) in the table below to determine the increase in cost and the increase in the percent of the
population that must be sampled when we want our inference to be more accurate, that is, we decrease
our margin of error.
What happens to cost as margin of error decreases?
(a)
Margin of Error
(b)
Sample Size
(c)
Total Cost
(d)
Cost of decreasing
margin by 1%
(e)
Percent of Population
to be sampled
5%
4%
3%
2%
1%
To keep things consistent, use the following information each time (the only item that should be changed
is the
margin of error
):
Page 1 of Demo: (Use all defaults)
Sampling method: Simple Random sampling
Dependent variable: Mean
Purpose of research: Estimate Mean
Page 2 of Demo: (Click calculate research costs)
Main goal: Find minimum sample size, given a fixed
error
Optional analyses: Calculate Research Costs
Page 3 of Demo:
Margin of error: This will change each time
beginning with .05 down to .01
Significance level: .10 (default for the demo)
Page 4 of Demo:
Total Population size: 1000
Standard Deviation: 1
Page 5 of Demo:
Unit Cost (the average direct cost per completed
survey): 10
Overhead (the
total
indirect cost (consultant fees,
office supplies, etc.) which are largely unaffected by
the number of surveys completed): 0