Question

Null hypothesis (H₀): The true difference in mean hemoglobin change for pregnant women not exposed to herbicides versus those who are somewhat exposed is 0 g/dL. (µ_bottle – µ_both = 0 g/dL)

Research hypothesis (H₁): The true difference in mean hemoglobin change for pregnant women not exposed to herbicides versus those who are somewhat exposed is not 0 g/dL. (µ_bottle – µ_both ≠ 0 g/dL)

SAS Output:

The TTEST Procedure

Variable: change

group	Method	Mean	95% CL Mean	Std Dev	95% CL Std Dev
2		2.0326	1.9846	2.0806	0.4329	0.4015	0.4696
3		3.3348	3.2932	3.3763	0.4192	0.3918	0.4507
Diff (1-2)	Satterthwaite	-1.3022	-1.3655	-1.2388

Method	Variances	DF	t Value	Pr > |t|
Satterthwaite	Unequal	663.42	-40.36	<.0001

a. What is the 95% confidence interval for the difference in group means? Please write in interval notation: (smaller, larger)

b. What is the interpretation of the 95% confidence interval for the difference in group means?

c. Would you reject or fail to reject the null hypothesis? (Use α=0.05.) Why?

d. What is the conclusion of the hypothesis test? (Write in terms of the research hypothesis.)

Answer 1

a)

95% CI (-1.3655 ,-1.2388)

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B)

WE ARE 95% CONFIDENT THAT TRUE MEAN DIFFERENCE BETWEEN LIE IN THIS INTERVAL

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C)

P VALUE < 0.05 , REJECT Ho

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d)

conclusion : there is enough evidence to conclude that  The true difference in mean hemoglobin change for pregnant women not exposed to herbicides versus those who are somewhat exposed is not 0 g/dL.

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Please let me know in case of any doubt.

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