Seminar #12

Rhajiv Ratnatunga Honors STAT 1000

Bone marrow transplantation is one of the most common treatments for acute leukemia.

The purpose of this study was to consider the effects of bone marrow transplantation with a radiation-free conditioning regimen.

Patients were given different drugs in two groups at four different hospitals (two in US and two in Australia)

137 patients were studied (97 in the US and 40 in Australia) from 1984 to 1989.

This study was….

a) Retrospective observational study

b) Prospective observational study

c) Experiment

c – This was an experiment because the experimenters controlled different variables (specifically, the types of drugs given) in order to see their effect on recovery from or relapse into acute leukemia. The study was two sample since the study looked at the effects of two independent drug treatments.

The experimenters grouped individuals into many different risk categories.

Donor age and recipient age was one of the risk categories.

Since we start with a recipient who needs a donor...

The explanatory variable is

The response variable is

recipient age

donor age.

The regression equation isRecipient = 8.89 + 0.684 Recipients

S = 6.55008 R-Sq = 54.0% r = .734846 (fairly strong + relationship)

Positive slope of .790 means that for every additional year in the age of the donor, we expect the age of the recipient to go up around 9.6 months.

Fairly strong positive correlation supports this relationship.

None of the recipients were less than 1 year old

Intercept is of no interpretive value since it deals with a recipient age of 0

The s value of 6.55008 meant that ages predicted by the regression line tended to be off on average by around 6.5 years from the actual ages.

This difference makes sense when looking at the r value of the correlation r = .734846 (fairly strong + relationship)

Why are ages positively correlated?Bone marrow transplantation need

exact matches of Human leukocyte antigen

Highest percentage of matches found among….

Siblings

Bimodal

Parent donation vs. Sibling donation

Was this study reported from a sample or population?

Sample

The experimenters tried to categorize risk factors prior to transplantation in order to reduce confounding variables.

Objective determinations such as “death” and “remission” do not involve bias.