Planned Value, often called Budgeted Cost of Work Scheduled (BCWS), is the cost allocated for the scheduled work to be completed at any given point in time. In other words, it is the estimated value of the project tasks that should have been completed. It helps project managers to determine if project cost and schedule are progressing as planned. PV sets the baseline against which the actual costs (AC) and earned value (EV) will be compared.

Earned Value, also known as Budgeted Cost of Work Performed (BCWP), measures the actual performance of the project. Essentially, it is the value of the work that has actually been done expressed in terms of the approved budget allocated for that work. By comparing the EV to PV, we can determine whether we are ahead or behind our planned schedule. Conversely, by comparing EV to AC, we can judge whether we are under or over our planned budget.

Actual Cost, also known as Actual Cost of Work Performed (ACWP), is the total cost incurred for the work performed on the project activity during a specific time period. This is not estimated or budgeted cost, but the real cost that has been incurred for completing the project work. AC is used in calculating cost variance (CV) and cost performance index (CPI) which help determine whether the project is under or over budget.

Cost variance is a measure of cost performance on a project. It is the algebraic difference between earned value (EV) and actual cost (AC). CV = EV - AC. It helps determine if the project is under budget (CV > 0) or over budget (CV < 0). Maintaining a positive cost variance throughout the project suggests that the project is efficiently using its resources.

Schedule variance is a measure of schedule performance on a project. It is the algebraic difference between the earned value (EV) and the planned value (PV). SV = EV - PV. It helps determine if the project is ahead of schedule (SV > 0) or behind schedule (SV < 0). A positive schedule variance means that the project is ahead of its schedule, while a negative variance indicates a delay in the project.

The Cost Performance Index (CPI) is a measure of the cost efficiency of budgeted resources, expressed as a ratio of earned value to actual cost. If a project's CPI is less than 1.0, it means the project is over budget. Conversely, a CPI of greater than 1.0 indicates the project is under budget. The CPI is a crucial measure because it shows the project manager and stakeholders how much value the project is delivering for the money that’s being spent on it, allowing them to make crucial future budgeting decisions.

The Schedule Performance Index (SPI) is a measure of schedule efficiency, expressed as a ratio of earned value to planned value. If a project's SPI is less than 1.0, it means the project is behind schedule. Conversely, an SPI of greater than 1.0 indicates the project is ahead of schedule. The SPI focuses on the efficiency of the time utilization on the project, enabling project managers to better manage their schedules and providing valuable guidance on whether there may be a need to adjust resources, or priorities.

Estimate at Completion (EAC) represents the forecasted value of costs at the end of the project. It provides an estimate of what the project is expected to cost. Normally, this estimate is a combination of the money already spent (actual costs) and the estimate to complete (the remaining work). This measure provides project managers and stakeholders with a tool to predict the total project cost based on current project performance and helps them to ascertain whether budget adjustments are necessary.

Estimate to Complete (ETC) is the expected cost to finish all the remaining project work. The ETC can be considered as the future a cost performance index if the project continues as is. This is a crucial measurement as it helps to identify cost overruns in early stages of the project. It represents the forecast of remaining budget needs based on both cost performance and schedule performance.

To-Complete Performance Index (TCPI) is a projection of the anticipated performance required to achieve a goal. The TCPI can forecast how much efficiency must be achieved on the remaining work to meet a financial commitment. In essence, this metric tells us the cost performance index (CPI) that we need to hold going forward from this point in time to stay within the budget. It is a vital measure as it allows project managers to understand what future productivity levels must be in order to meet a specific budget or deadline.