Saturday, October 8, 2011

Figure Misadventures: **

This week in lab meeting, we covered a recent paper from the Mizrahi lab in Israel. Two points.

First, it's amazing how standards have increased. They performed chronic, in vivo, two-photon imaging over nine months, and used a dopaminergic-specific GFP line, and all they got was a Journal of Neuroscience paper. Now, there are reasons it's only J. Neuroscience: they counted cells bodies, not spines, and as everyone knows, cells exist for their spines to be counted; and their only non-control result was a 13% increase in dopaminergic neuron number in the olfactory bulb (below, lower panel).

c. Gains and losses of dopaminergic neurons in the olfactory bulb.  Note the super-significant ** (p<0.01!!!) at the third time point. d. Overall change in dopaminergic neuron number. 13%!.
What I really love, though, is the ** in the top panel of the figure, denoting p < 0.01, compared to those dirty *s over the other data points (p < 0.05). To get those stars performed repeated Student's t-test rather than doing an ANOVA, which is such a ubiquitous sin it's like Catholics using birth control. It's indisputable that there are more neurons gained than lost neurons at all time points. Yet one of the authors was compelled to include the **. Why? Would someone not believe the data if one of the points was p < 0.01? Is there some standard that all p-values < 0.01, must get a **? Are they trolling anal-retentive people, like me? Are they going to focus their research on that time point? Or, more likely, someone thoughtlessly figured, "why not?"

Extra *s are not inherently dumb, but they reflect imprecise thinking. In science, we can't hope to be that certain (p <0.01). We can only observe until we're pretty sure, then wait for independent verification. I worry that people who note **s when they're not meaningful might be prone to noticing *s when they don't exist.

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