Equations
Inline equations
Inline equation fit within the paragraph. E.g. P(y < Y|\theta) = \alpha. This works OK with short equations. More complex, taller equation will altered to minimize their height, e.g. \bar{X} = \sum_{i = 1}^NX_i. i = 1 and N are placed beside \sum instead of above it. This doesn’t work with even taller equations like breaks, e.g. \frac{X}{Y}. In this case the font size is decreased. Complex equations like \frac{\sum_{i = 1}^NX_i}{\frac{\sum_{j = 1}^NY_j}{N}} require a larger interline distance. A stand alone equations is a better solution for complex equations.
Stand alone equations
P(y < Y|\theta) = \alpha
\bar{X} = \sum_{i = 1}^NX_i
\frac{X}{Y}
\frac{\sum_{i = 1}^NX_i}{\frac{\sum_{j = 1}^NY_i}{N}}
Numbered equations
\bar{X} = \sum_{i = 1}^NX_i \tag{1}
\frac{X}{Y} \tag{2}
\frac{\sum_{i = 1}^NX_i}{\frac{\sum_{j = 1}^NY_j}{N}} \tag{3}