In: Statistics and Probability
A program to decrease littering was carried out in four cities in California’s Central Valley starting in August 2007. The amount of litter in the streets (average pounds of litter collected per block per day) was measured during July before the program started and then the next July, after the program had been in effect for a year. The results are as follows:
City |
July 2007 |
July 2008 |
Fresno |
9 |
2 |
Merced |
10 |
4 |
Bakersfield |
8 |
9 |
Stockton |
9 |
1 |
Given:
A program to decrease littering was carried out in four cities in California’s Central Valley starting in August 2007.
The amount of litter in the streets (average pounds of litter collected per block per day) was measured during July before the program started and then the next July, after the program had been in effect for a year. The results are as follows:
City |
July 2007, X |
July 2008, Y |
d = X-Y | d2 |
Fresno |
9 |
2 |
7 | 49 |
Merced |
10 |
4 |
6 | 36 |
Bakersfield |
8 |
9 |
-1 | 1 |
Stockton |
9 |
1 |
8 | 64 |
Total | d= 20 | d2 = 150 |
Hypothesis test:
In word :
Ho : There a significant decrease in the amount of litter.
Ha : There a significant decrease in the amount of litter.
In symbol :
Ho : = 0
Ha : < 0
Conclusion : At 0.01 significance level, there is not a significant decrease in the amount of litter.