# Is it possible to have too much data? When should I subsample? [duplicate]

Social science PhD student here looking for a little help.

I set out to collect around 300 online surveys for a study, but ended up with over 4,000. At that sample size should I sub-sample my results because it's more likely that significant results will be found because of the sample size?

Thanks.

• Significance tells you if the effect is 'real' or not, not how much it matters. Look at the magnitude of the effects to see which ones are actually important in explaining the phenomenon you're researching. – conjectures Jun 10 '14 at 20:50
• I think the bigger concern would be the likely effect of a self-selected sample on your inference. – Glen_b Jun 10 '14 at 21:02

This is generally a good thing, so long as it is presented in a helpful way. For example, reporting confidence intervals in sensible units (the intervals will be narrower with a larger sample) rather than $p$ values can help the reader understand whether a reported result is worth worrying about.