posted by Katie .
I have a stats exam tomorrow and I understand the material pretty well, but i sort of get confused. because my homework comes from a section, i know what formulas to use, but i took a practice test and i'm having a hard time identifying whether a problem is poisson or binomial? are there any key or specific terms i should know for each type of problem? thank you
i know how to use both poisson and binomial tables and i know the formulas for calculating means and standard deviations, i just have a hard time figuring out when i need to use the binomial formulas or when to use the poisson formulas.
Here's a few suggestions:
1. Binomial distributions are broken down into "success/failure" or "yes/no" or "agree/disagree" type of problems. You have two concepts. One example might be 42 out of 150 people agree with a particular candidate's point of view. This means 108 people out of 150 do not agree. You can convert these proportions or percentages to decimal form when using the appropriate formulas.
2. If a problem uses some sort of rate or time interval, then a Poisson distribution might be your best bet. The following is an example:
A statistics professor finds that when she schedules an office hour for student help, an average of 2.2 students arrive.
These are just a few suggestions. I hope this helps.