You must determine if two fabrication processes generating Part X are significan

Question

You must determine if two fabrication processes generating Part X are significantly different from each other. At this point, you don't know if the mean length of parts made with Fabrication Process 1 is greater than or less than that of Fabrication Process 2 Are the population means of the two processes statistically different with a 05% confidence level? Write both the null and alternate hypotheses. The descriptive statistics are as follows: Fabrication Process 1: Xbar_1= 23.6cm, S_1 = 7.1cm, n_1 = 15 Fabrication Process 2: Xbar_2=19.1cm, S_1 = 6.5cm, n_2 = 17 Now. you must determine if a new cholesterol drug is effective. You know that the drug lowers blood pressure but are not sure if the difference is significant. With 99% confidence, is there a statistically significant difference in blood pressure (mmHg) before and after administration of the drug? Five patients were sampled before and after drug administration. Write the null and alternate hypothesis.

Explanation / Answer

1.

Formulating the null and alternative hypotheses,              
              
Ho:   u1 - u2   =   0  
Ha:   u1 - u2   =/   0  

At level of significance =    0.05          

As we can see, this is a    two   tailed test.      
Calculating the means of each group,              
              
X1 =    23.6          
X2 =    19.1          
              
Calculating the standard deviations of each group,              
              
s1 =    7.1          
s2 =    6.5          
              
Thus, the standard error of their difference is, by using sD = sqrt(s1^2/n1 + s2^2/n2):              
              
n1 = sample size of group 1 =    15          
n2 = sample size of group 2 =    17          
Thus, df = n1 + n2 - 2 =    30          
Also, sD =    2.417842175          
              
Thus, the t statistic will be              
              
t = [X1 - X2 - uD]/sD =    1.861163663          
              
where uD = hypothesized difference =    0          
              
Now, the critical value for t is              
              
tcrit =    +/-   2.042272456      
              
Also, using p values,              
              
p =    0.072546277          
              
As |t| < 2.042, and P > 0.05, then we fail to reject Ho.

There is no significant evidence that at 95% confidence that the population means of the two processes are different. [CONCLUSION]

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If you use another method/formula in calculating the degrees of freedom in this t-test, please resubmit this question together with the formula/method you use in determining the degrees of freedom.

Please submit the next part as a separate question also. That way we can continue helping you! Thanks!

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