Question

The level of various substances in the blood of dialysis patients is of concern because kidney failure can lead to nutritional problems. A researcher performed blood test on several dialysis patients on six consecutive clinic visits. One variable measured was the level of phosphate in the blood. Phosphate levels for an individual tend to vary normally over time. The data on one patient, in milligrams of phosphate per deciliter (mg/dl) of blood, are shown below:

6.1 5.9 5.4 6.2 6.4 6.0

a) Calculate the sample mean and sample standard deviation for this data set. You may use your calculator and simply the results below.

b) Find and interpret a 90% confidence interval for this patient’s true mean phosphate level. Be sure to incorporate the units of measure in your answer.

Answer 1

( a )

Sample mean = 6.00

Sample standard deviation = 0.3406

standard error = 0.139

( b )

We are 90% confident tha the true mean phosphate level for this patient’s lies between 5.719 and 6.281