Question

Four different designs for a digital computer circuit are being studied to compare the amount of
noise present. The following data have been obtained:

Circuit Design	Noise Observed
1	19	20	19	30	8
2	80	61	73	56	80
3	47	26	25	35	50
4	95	46	83	78	97

a) Identify the following:
 Factor(s):
 Treatment(s):
 Response:
b) Are the data normally distributed?
c) Which of the following tests would you use if you wanted to determine if there are
differences in noise present for all four designs? (SELECT ONE CORRECT ANSWER)
 T-test, two independent samples
 Chi-sq test
 One-Way ANOVA
 Kruskal-Wallis test
d) If the same amount of noise present for all four designs? Use α=0.05.

Answer 1

A) FACTOR and Treatment are same :Type of circuit designs.

Circuit 1 , Circuit 2 , Circuit 3 and Circuit 4

Response Variable: Amount of noise present

b) No data are not normally distributed.

By using SPSS we have

b) We can see it is multi modal distribution.

c) We will use Kruskal-Wallis test ( Non parametric version of One way ANOVA)

d) NULL HYPOTHESIS H0: The same amount of noise present for all four designs

ALTERNATIVE HYPOTHESIS Ha: The same amount of noise NOT present for all four designs

By using SPSS

Chi square statistic = 14.931

Degrees of freedom=3

P value= 0.002

Since P value smaller than the level of significance 0.05 therefore SIGNIFICANT

Decision: REJECT NULL HYPOTHESIS H0.

Conclusion: We have sufficient evidence to conclude that the same amount of noise is NOT present for all four designs at 0.05 level of significance.