I am analyzing a temperature image using a land cover map with the overall goal to prepare a barplot where I report the mean ± StDev temperature for each land cover class. To do so I assigned each pixel to a land cover class and then I estimated the mean and the standard deviation from all the pixels of each class. What troubles me though is that the number of pixels between classes is not the same, for instance class A might have 8 pxls, class B 26 pxls and class C 140 pxls. Hence the statistics I calculate correspond to different-sized populations, which doesn't feel right. Another option is to select from all classes the same number of pixels, e.g. 8; however in that case I include from class A the entire pixel population, from class B 31% of its members and from class C only ~6%, which also doesn't feel right. Hence I would like to ask for your suggestions, is this a problem and how should I approach it? What is the best-practise in such cases?
Thank you for your help!