What CI should I use when finding Margin of Error? I've begun an assignment where I collect my own data. The assignment is now asking me to find margin of error with the collected data. I have nearly everything I need for the equation with the exception of the Confidence Interval.
Do you think it would matter what I choose? whether it be 90% CI for population mean or 95% etc. 
Sorry about this question being a little dumb. 

It depends how accurate you want your results to be. An $x$% C.I. for the population mean is such that if you repeat the experiment / data collection $100$ times, the mean should lie within the C.I. $90$ times. So for any given experiment / set of data, there's a $90$% chance the population mean lies within the C.I. 
