I am pretty new to statistics and I'd like to get pointers on the correct way to do this.
I have a dataset in which I'm interested in the 50th and 90th percentile. I'd like to take a sample of that set but still preserve (with some margin of error) the 50th and 90th percentiles.
I am unsure how to approach this -- I know the t-test compares means, but it doesn't seem to me it can be used for my purposes. My data also has a strong skew (long right tail). If someone can suggest an algorithm or approach to this I would much appreciate it.
I am not writing a paper, just need to drop a large portion of data in a reasonable manner.