Question

What effect does noise pollution have? Mathews and Canon (1975) had a person with a cast on one arm get out of a car and drop an armload of books in front of pedestrians. Will the pedestrians help? Sometimes there was a loud gasoline lawn mower operating (Noise) nearby when the books were dropped and sometimes the mower was not operating (No Noise). Of the 25 pedestrians who were in the Noise condition, 4 helped. Of the 25 pedestrians who were in the No Noise condition, 20 helped. Analyze the numbers and write an explanation of the effects of noise pollution. Please show how you allocated the frequency before calculating. Please show all work for credit. Also show the critical value.

Answer:

Noise

No Noise

Helped

Did not help

Answer 1

The hypothesis being tested is:

H0: There is no effect of noise pollution

Ha: There is an effect of noise pollution

		Noise	No Noise	Total
Helped	Observed	4	20	24
	Expected	12.00	12.00	24.00
	O - E	-8.00	8.00	0.00
	(O - E)² / E	5.33	5.33	10.67
Did not help	Observed	21	5	26
	Expected	13.00	13.00	26.00
	O - E	8.00	-8.00	0.00
	(O - E)² / E	4.92	4.92	9.85
Total	Observed	25	25	50
	Expected	25.00	25.00	50.00
	O - E	0.00	0.00	0.00
	(O - E)² / E	10.26	10.26	20.51
		3.841	critical value
		20.51	chi-square
		1	df
		5.92E-06	p-value

The p-value is 0.0000.

Since the p-value (0.0000) is less than the significance level (0.05), we can reject the null hypothesis.

Therefore, we can conclude that there is an effect of noise pollution.

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