cientists and engineers frequently wish to compare two different techniques for measuring or determin- ing the value of a variable.

Scientists and engineers frequently wish to compare two different techniques for measuring or determin- ing the value of a variable. In such situations, interest centers on testing whether the mean difference in measurements is zero. The  article  Evaluation of the Deuterium Dilution Technique Against the Test Weighing Procedure for the Determination of Breast Milk Intake (Amer. J. Clin. Nutrit., 1983: 996—1003) reports the accompanying data on mea- suring amount of milk ingested by each of 14 randomly selected infants.

a.   Is it plausible that the population distribution of differences is normal?

b.   Does it appear that the true average difference between intake values measured by the two methods is something other than zero? Deter- mine the P-value of the test, and use it to reach a conclusion at signi cance level .05.

c.    What happens if the two-sample test is (incor- rectly) used? Hints1 = 352.970,s2 = 234.042.

 

 

Infant

 

 

Isotopic

1509

1418

1561

1556

2169

1760

1098

1198

1479

1281

1414

1954

2174

2058

Test

1498

1254

1336

1565

2000

1318

1410

1129

1342

1124

1468

1604

1722

1518

Difference

11

164

225

-9

169

442

-312

69

137

157

-54

350

452

540

 

 

Method            1          2          3          4          5          6           7          8          9         10        11        12        13        14

 

 

 

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