An indicator is a predefined variable that identifies a direct difference in quality and/or quantity over a specific period of time. As a unit of measurement, it allows you to judge whether an intervention was successful or not. Indicators simplify complex problems and turn them into measurable dimensions. For example, if you’re training for a long jump, your main metric will be “the extra inches you can jump,” after you’ve improved your technique as you workout. Indicators are often called performance indicators (PIs), which are divided into results indicators or performance indicators. Performance indicators are well-defined qualitative and quantitative metrics that reflect the performance of an organization or project. Output indicators are used to assess whether and to what extent output has been achieved. Performance indicators are used to assess whether expected results have been achieved. There are four types of indicators: input indicators, output indicators, outcome indicators and impact indicators.