What does the fact that 70% of the female crickets move towards the loudspeaker playing the male cricket chirping indicate?
The fact that 70% of the sample crickets move towards the loudspeaker indicates that there is a trend for female crickets to respond to the sound. There can still be variables that are unknown that could effect both the migration and the non-migration, however.
Perhaps some of the 30% that did not migrate were not part of the same species of cricket that the sound came from. Perhaps the female cricket was not at a stage where she was biologically prepared to reproduce with the male crickets. Maybe the female crickets were not listening to the loudspeaker and were distracted by another sound. I'm not so sure I know enough about the inner workings of the brain of a cricket to know exactly what thier instincts are telling them to do.
On the other hand, 70% is a pretty large percentage of crickets doing the same thing. Sure some of the crickets may have randomly wandered over to the loudspeaker out of boredom, but the trend indicates some sort of reason to follow the sound. In trying to put the same experiment into human terms--the only terms I feel any confidence making any conclusions upon--the same experiment would be pretty indicative if one particular sound interested women enough to at least check out the loudspeaker.
The reading, "The neurobiology of cricket song," lends some credence to the thought that the female crickets are attracted to only the sound of thier same species, but also fails to address the possibility of female crickets attracted to the sound for solely mating puposes--neglecting pure cricket curiousity.
"would be pretty indicative of ...?" Sure, there is evidence that male sound attracts female crickets. Its that it doesn't ALWAYS do so that poses the next questions. You've done a pretty good job of starting to list some reasons (and hence of suggesting possible things that must be somehow in the box). We'll try and formalize this tomorrow. PG