I am comparing length of stay after laparoscopic and open appendectomy in over 160000 patients. LOS is typically a skewed variable so I use the median and interquartile range and ranksum test to describe the result, which is 2, IQR 2-3 and 2, IQR 2-4, p&lt;0.0001. So there is a highly significant difference but it does not show that well in the median and IQR. 

The difference in length of stay is very small. This finding is a negative finding but still interesting as it goes against what most people think about LOS after laparoscopic appendectomy. That is why I want to report on the difference in LOS which is not evident if I only report median and IQR with p-value.

The arithmetic mean (3.1 vs 2.8 and a difference of 0.3 days) is not recommended as the distribution is skewed. I wonder if any other measure could be used like, geometric mean (2.5 vs 2.3, difference 0.2 days) or harmonic mean (2.1 vs 1.9 days, difference 0.2 days)?  When can I use geometric mean or harmonic mean? 

I am inclined to use the harmonic mean which comes closest to the median and gives a difference of 0.2 days. Is this incorrect?


Question: Is it possible to jailbreak an iPad 2 (A1395) after updating to iOS 6.0.1?
Answer: This is no longer true; Both answers were written before evasi0n came out. Now it's more than possible to JB 6.x devices, in fact up to 6.1.1/6.1.2.

As for backing up, you don't need to back up Cydia - it gets reinstalled anyway. What I would back up are any manually installed (i.e. hackulous-type) apps you may have (cd to /var/mobile/Applications, then do a tar)