I am interested to know what substantive differences exist between the
techniques of genetic linkage and genetic association.  Both methods
are used to determine the relationship between a particular genotype
and a phenotype and I know that they are different??I just don?t know
how they are different.  Help!

Although these two concepts are related to each other, they are not
the same thing.

Term linkage is usually used to talk about movement of genes during
recombination events. Concept is very simple, if you imagine two genes
located in close proximity to one another on the chromosome. During
recombination event(meiosis), these genes will likely to stay
together, and we call them linked.  A simple example is study of fly
populations, where eye color is linked to shape of wings, because
genes responsible for development of these phenotypes are located on
the same chromosome not far from each other.


Association studies usually refer to the experiments where researcher
notes a phenotype difference between two groups of individuals and
tries to find genes that are responsible for phenotype. For example,
researcher would note that individuals in a group A have more heart
attacks than in control group B. Association study would than focus on
mapping the differences between two groups by looking at mutations
present in group A and absent in group B.

Hope this helps.
http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=iga.section.899
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=association+study+AND+cmed%5Bbook%5D+AND+16809%5Buid%5D&rid=cmed.section.5117

thanks.  that's exactly what I was looking for.