Alternative Equation Formats

$${\displaystyle \begin{array}{rlrl}{n}_{i\cdot <!--\; \cdot \; -->}& =\underset{j}{\sum <!--\; \sum \; -->}{n}_{ij}& & \text{(row totals)}\\ n_{\cdot <!--\; \cdot \; -->j}& =\underset{i}{\sum <!--\; \sum \; -->}{n}_{ij}& & \text{(column totals)}\\ n& =\underset{i}{\sum <!--\; \sum \; -->}\underset{j}{\sum <!--\; \sum \; -->}{n}_{ij}& & \text{(overall total)}\\ p_{ij}& =n_{ij}/n& & \text{(cell percentages)}\\ p_{i\cdot <!--\; \cdot \; -->}& =n_{i\cdot <!--\; \cdot \; -->}/n& & \text{(row percentages of total)}\\ p_{\cdot <!--\; \cdot \; -->j}& =n_{\cdot <!--\; \cdot \; -->j}/n& & \text{(column percentages of total)}\end{array}}$$

$${\displaystyle \begin{array}{rlrl}{n}_{i\cdot <!--\; \cdot \; -->}& =\underset{j}{\sum <!--\; \sum \; -->}{n}_{ij}& & \text{(row totals)}\\ n_{\cdot <!--\; \cdot \; -->j}& =\underset{i}{\sum <!--\; \sum \; -->}{n}_{ij}& & \text{(column totals)}\\ n& =\underset{i}{\sum <!--\; \sum \; -->}\underset{j}{\sum <!--\; \sum \; -->}{n}_{ij}& & \text{(overall total)}\\ p_{ij}& =n_{ij}/n& & \text{(cell percentages)}\\ p_{i\cdot <!--\; \cdot \; -->}& =n_{i\cdot <!--\; \cdot \; -->}/n& & \text{(row percentages of total)}\\ p_{\cdot <!--\; \cdot \; -->j}& =n_{\cdot <!--\; \cdot \; -->j}/n& & \text{(column percentages of total)}\end{array}}$$

\[ \begin{aligned} n_{i \cdot } & = \sum _ j n_{ij} & & \mbox{(row totals)} \\ n_{\cdot j} & = \sum _ i n_{ij} & & \mbox{(column totals)} \\ n & = \sum _ i \sum _ j n_{ij} & & \mbox{(overall total)} \\ p_{ij} & = n_{ij} / n & & \mbox{(cell percentages)} \\ p_{i \cdot } & = n_{i \cdot } / n & & \mbox{(row percentages of total)} \\ p_{\cdot j} & = n_{\cdot j} / n & & \mbox{(column percentages of total)} \end{aligned} \]