Question

A clinical study is designed to assess differences in albumin levels in adults following diets with different amounts of protein. Low protein diets are often prescribed for patients with kidney failure. Albumin is the most abundant protein in blood, and its concentration in the serum is measured in grams per deciliter (g/dL). Clinically, serum albumin concentrations are also used to assess whether patients get sufficient protein in their diets. Three diets are compared, ranging from 5% to 15% protein, and the 15% protein diet represents a typical American diet. The albumin levels of participants following each diet are shown below. (5 % Protein 3.1 2.6 2.9), (10 % Protein 3.8 4.1 2.9 3.4 4.2), (15 % Protein 4.0 5.5 5.0 4.8). Is there is a difference in serum albumin levels among subjects on the three different diets ? For reference, normal albumin levels are generally between 3.4 and 5.4 g/dL. I preferred EXCEL. Use Kruskall-Wallis Tests Thanks.

Answer 1

A clinical study is designed to assess differences in albumin levels in adults following diets with different amounts of protein. Low protein diets are often prescribed for patients with kidney failure. Albumin is the most abundant protein in blood, and its concentration in the serum is measured in grams per deciliter (g/dL). Clinically, serum albumin concentrations are also used to assess whether patients get sufficient protein in their diets. Three diets are compared, ranging from 5% to 15% protein, and the 15% protein diet represents a typical American diet. The albumin levels of participants following each diet are shown below. (5 % Protein 3.1 2.6 2.9), (10 % Protein 3.8 4.1 2.9 3.4 4.2), (15 % Protein 4.0 5.5 5.0 4.8). Is there is a difference in serum albumin levels among subjects on the three different diets ? For reference, normal albumin levels are generally between 3.4 and 5.4 g/dL. I preferred EXCEL. Use Kruskall-Wallis Tests

Excel Addon Megastat used.

Kruskal-Wallis Test
	Median	n	Avg. Rank
	2.90	3	2.50	5%Protein
	3.80	5	6.10	10%Protein
	4.90	4	10.00	15%Protein
	3.90	12		Total
			7.549	H (corrected for ties)
			2	d.f.
			.0229	p-value
		multiple comparison values for avg. ranks
		6.10	(.05)	7.48	(.01)
No.	Label	Data	Rank
1	5%Protein	3.1	4
2	5%Protein	2.6	1
3	5%Protein	2.9	2.5
4	10%Protein	3.8	6
5	10%Protein	4.1	8
6	10%Protein	2.9	2.5
7	10%Protein	3.4	5
8	10%Protein	4.2	9
9	15%Protein	4	7
10	15%Protein	5.5	12
11	15%Protein	5	11
12	15%Protein	4.8	10

Calculated test statistic H (chi square) =7.549, which is > chi square critical value 5.991 at 0.05 level of significance.

Ho is rejected.

We conclude that there is a difference in serum albumin levels among subjects on the three different diets.