1
Q
Confidence Intervals are
A
an interval of numbers
2
Q
Because x is within 0.2 units of μ, which is unknown, then μ is
A
likely to be within 0.2 units of x in 95% of the samples.
3
Q
8.1 confidence interval formula
A
x-MOE (EBM), x + MOE (EBM)
4
Q
difference between 8.1 and 8.2
A
8.1 sigma known
8.2 sigma unknown
5
Q
margin of error depends on
A
CL eg 90%, 95%
if not given use 95% (want 90 or higher)
6
Q
8.1 steps to conduct confidence intervals
A
- calculate mean (CL, a, a/2) sigma already known, find Z (z=za/2) score from mean (above)
- find EBM using formula
3.write confidence interval
4.interpret with %, what were finding, the between
7
Q
if we want to find n when sigma known
A
may need to do steps from above
always round the answer up to the next integer
8
Q
8.2 when sigma unknown we use
A
t chart
9
Q
df equals
A
n-1
10
Q
8.2 difference to finding z score
A
do all the steps to find za/2 but you do not find above
use df=n-1 and za/2 to locate z score then follow same steps
STATS 161
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