Next: An example from Wright
Up: Corrections for sampling error
Previous: Even more gory details11
If we return to the data that motivated this discussion, these are the
results we get from analyses of the
data from Isotoma
petraea (Table 1).
Table 2:
Comparison of Wright's
-statistics when ignoring sampling
effects with Nei's
and Weir and Cockerham's
.
| Method |
 |
 |
 |
| Direct |
0.1372 |
0.2143 |
0.3221 |
| Nei |
0.3092 |
0.2395 |
0.4746 |
| Weir & Cockerham |
0.5398 |
0.0387 |
0.5577 |
|
But first a note on how you'll see statistics like this reported in
the literature. It can get a little confusing, because of the
different symbols that are used. Sometimes you'll see
,
, and
. Sometimes you'll see
,
, and
. And it will seem as if they're referring to similar
things. That's because they are. They're really just different symbols
for the same thing (see Table 3).
Table 3:
Equivalent notations often encountered in descriptions of
population genetic structure.
|
|
Strictly speaking the symbols in Table 3 are the
parameters, i.e., values in the population that we try to
estimate. We should put hats over any values estimated from data to
indicate that they are estimates of the parameters, not the parameters
themselves. But we're usually a bit sloppy, and everyone know that
we're presenting estimates, so we usually leave off the hats.
Next: An example from Wright
Up: Corrections for sampling error
Previous: Even more gory details11
Kent Holsinger
2008-08-18