Science Buddies: "Ask an Expert"

Hey

I was wondering, why do scientists (when conducting experiments) need to sample from a population rather than using an entire population??

And....In an experiment, what are the disadvantages of having too small or too large of a sample size???

Thank you

Simply stated this is a matter of statistics. Statistical analysis shows us that smaller samples have a larger percentage of error compared to larger samples. When taking samples from an entire population may be impractical (as in an opinion poll) a sample is taken which is just large enough to produce an acceptable percentage of error. I hope that helps