# Statistics Case Study 1

Pages: 4 (688 words) Published: July 10, 2005
Statistics
Case Study-1

AgeWeeks Employed
5521
3018
2311
5236
4119
2512
427
4525
256
4021
2513
2511
5934
4927
3318
3520

a.
AgeWeeks Employed
Mean37.75Mean18.6875
Standard Error2.974195Standard Error2.188452
Median37.5Median18.5
Mode25Mode21
Standard Deviation11.89678Standard Deviation8.753809
Sample Variance141.5333Sample Variance76.62917
Kurtosis-1.17143Kurtosis-0.21626
Skewness0.337402Skewness0.522601
Range36Range30
Minimum23Minimum6
Maximum59Maximum36
Sum604Sum299
Count16Count16
Confidence Level(99.0%)8.764138Confidence Level(99.0%)6.44877

b. 99% confidence interval estimate for mean age of newly hired employees;

37.75 ¡V 8.76 = 28.99
to
37.75 + 8.76 = 46.51

c. Hypothesis:

Decision Rule: Reject Ho if t > t-critical
Do not reject Ho if t < t-critical

t-critical = t0.01,15 =2.602

0.771 < 2.602
Therefore, at a 99% Confidence Level the Null Hypothesis can not be rejected and we can not state that Riverside¡¦s mean duration of employment weeks is any greater than the mean duration of employment weeks within the rest of California.

d. Is there a relationship between the age of a newly employed individual and the number of weeks of employment?

By using a scatter plot and plotting the number of weeks employed in respect to the ages of the workers, you can see that the points are distributed along a straight line. The number of weeks employed increase positively as the age of the worker increases. Therefore it is safe to say that there is a positive correlation between the ages of newly employed workers and the number of weeks they are employed.

Textbook Exercise 7.6, The Trash Bag Case

Text Problem 7.6:

n =40
mean =50.575
std dev. =1.6438

a.
95% =0.509408783m =50.06559122
m =51.08440878

99% =0.669478969m =49.90552103
m =51.24447897

b.Yes, we can be 95% confident that the trash...