BACKGROUNG FOR THE QUESTIONS : Multiple sclerosis (MS) is thought to be an autoimmune disease that affects

BACKGROUNG FOR THE QUESTIONS :

Multiple sclerosis (MS) is thought to be an autoimmune disease that affects the central nervous system (CNS). The CNS consists of the brain, spinal cord and the optic nerve.

There are many types of MS. People with relapsing and remitting type of MS (RRMS) experience clearly defined flare ups of the disease. About 85% are initially diagnosed with the RRMS.

In this study ANOVEX (60 mg) was compared to a placebo injection for the treatment of RRMS in 426 patients. There were 217 subjects in the ANOVEX group and 219 in the placebo group, with 24 months of follow up period. The data contains the information for the following variables:

subject identifier
treatment group(Anovex or placebo)
site identifier
gender(male or female)
race(black, white, Hispanic ,others)
age at screening(treat as continuous)
EDSS at baseline
EDSS group (reclassification of EDSS at baseline)
PASAT 2 number of letter correct at baseline
PASAT 2 number of letter correct at 24 month

The EDSS score is a composite score based upon an extensive neurological exam of 7 function systems and an ambulation component. It is important to note that the EDSS score is not a linear function of the disease status-it is a stepped function from 0 to 10 in 0.5 increment (except 0 -1)

The PASAT 2 score is the one component of Multiple Sclerosis Function Composite (MSFC).The PASAT 2 score is measured as the number of correct responses (total possible 60). It can be treated as continuous variable and is used to measure the cognitive function. The higher the score, the better the cognitive function.

Question no 1.

Describe the two groups at the beginning of study. The overall question is this: are the two groups comparable in terms of: age, sex and race, baseline PASAT 2?

Describe these two groups and then, in a table show – separately for each group- the means, SD’s and 95%CI on the means for continuous age variable. In a text or table, describe the proportion of female in each treatment group. Determine the approximate combination of race group from 4 groups into 2 groups for the analysis but fully describe the variables.

Test the quality between the groups:

1a) can we conclude that the two groups have different mean age?

1b) can we conclude that the two groups have different standard deviation age?

1c) can we conclude that the two groups have different proportion of females?

1d) can we conclude that the two groups have different baseline PASAT 2 score?

1e) MS is approximately two to three times more common in women than men, suggesting that hormones may also play a significant role in determining susceptibility to MS. Are the proportions of females in this study different from the expected proportion of females with RRMS of 67.5%?

If you conclude that the groups have a different average /proportion, then state (in a sentence or by clearly referring to tabled values) the 95% CI on the difference. You need not report a 95 % CI on the standard deviation within each group nor the 95% CI on the difference between the SD’s (1b)

Question 2:

Considering the both groups together (ignore the treatment group), is there a relationship (correlation) between AGE and the PASAT 2 measurement?(use no more than a few sentences to answer the question)

Solution: