Standard error in mean - Analyze particles

I am running ‘Analyze Particles’ and it works fine, but I would like to get an error on the ‘Mean’ values (from the Results table). I know I can use Set Measurements to include various outputs in my results, but I don’t know how to get the standard error in the mean. Because I do have the standard deviation, just knowing the total number of pixels in my particle that’s being analyzed also solves my problem (however, I also don’t know how to get that). Or is ‘Area’ the number of pixels??

See this link how this is calculated in the particle analyzer (8-neighbour connected):

http://imagejdocu.tudor.lu/doku.php?id=faq:technical:what_are_the_algorithms_used_to_calculate_particle_area_and_perimeter

Why 8-connected, see discussion here:

http://imagej.1557.x6.nabble.com/Why-is-Particle-Analyzer-8-connected-td5012756.html