Often times, in python's scipy library's statistical tests(e.g. Fisher Exact Test), there is an option for two-tailed or single tailed. But for single-tailed it says "less" or "greater." I don't quite understand what it means when it states:
Use a one-sided alternative hypothesis (also known as a directional hypothesis) to determine whether the population parameter differs from the hypothesized value in a specific direction. You can specify the direction to be either greater than or less than the hypothesized value. Source
Can someone please clarify this? What do they mean by direction? If I have a one tailed distribution with the mean close to 0 and no negative values, then what exactly would "less" do and "greater" do?
The x-axis is # of samples and y-axis is number of components of interest and each sample is an image.