Breakeven Analysis: Breakeven analysis is a fundamental tool in managerial accounting that helps businesses determine the point at which total revenue equals total costs, resulting in no profit or loss. It allows managers to understand the relationship between fixed costs, variable costs, and the sales price per unit, thus helping them make informed decisions about pricing, production, and sales strategies.

Personal observation: Personal observation generally refers to the act of watching and noting the behaviors or characteristics of something. It is not specifically a technique used to study the relationship between costs, volume, and profits.

Statistical Reports: While statistical reports can provide valuable data for decision-making, they are not inherently a specific technique for studying the relationship between costs, volume, and profits.

Budgetary Control: Budgetary control involves the process of creating budgets, comparing actual results with the budgeted figures, and taking corrective actions as needed.