One assumption of the test in Problem 10.68 is that the distribution of serum retinol is approximately

Question:

One assumption of the test in Problem 10.68 is that the of serum retinol is approximately normal. To verify this assumption, the investigators obtained a frequency of serum retinol at year 0 among males in the vitamin A group, with data as shown in Table 10.32.

Table 10.32 Distribution of serum retinol in a retinitis-pigmentosa population

Serum-retinol group (Î¼mol/L) ______________ n

‰¤1.40 €¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦.. 6

1.41ˆ’1.75 €¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦. 22

1.76ˆ’2.10 €¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦. 22

2.11ˆ’2.45 €¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦. 20

‰¥2.46 €¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦.. 3

€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦€¦.. 73

Perform a statistical test to check on the normality assumption. Given your results, do you feel the assumption of normality is warranted? Why or why not?

Ophthalmology

A 5-year study among 601 participants with retinitis pigmentosa assessed the effects of high-dose vitamin A (15,000 IU per day) and vitamin E (400 IU per day) on the course of their disease. One issue is to what extent supplementation with vitamin A affected their serum-retinol levels. The serum-retinol data in Table 10.31 were obtained over 3 years of follow-up among 73 males taking 15,000 IU/day of vitamin A (vitamin A group) and among 57 males taking 75 IU/day of vitamin A (the trace group; this is a negligible amount compared with usual dietary intake of 3000 IU/day).

Table 10.31 Effect of vitamin A supplementation on serum-retinol levels

Year 0 Year 3 Retinol (mmol/L) Vitamin A group Trace group Mean + sd Mean + sd 73 1.89 + 0.36 2.06 + 0.53 57 1.78 + 0.30

Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...