ProjectFlightDeck

Concept: The Schedule Performance Index for time (SPIt) is the ratio between the time earned on a project (i.e., the Earned Schedule—see April 19, 2015 post) and the time actually consumed.

We gauge the efficiency of schedule performance using threshold values for the SPIt. The starting points for threshold values are represented in the following table.

Practice: The threshold values are heuristic, rather than deterministic. That means we adjust the values through trial-and-error on each project, rather than using them as fixed points. For example, on one recent project, we extended the green zone down to .85 and dropped the red zone threshold to .7. Rationale: it was early in the project, the team was newly formed, and we wanted to build momentum. Once the team became habituated to being in the green zone, we tightened the thresholds.

In our experience, an individual reading in the .9 to 1.0 range is not a concern. It is likely that such a shortfall will be balanced by higher efficiency in the future. Similarly, an individual reading in the 1.0 to 1.1 range is not an issue. Such variations naturally occur in projects.

If individual readings occur outside the green zone, the response is different. In the .8 to .9 range, and even more, in the sub-.8 range, the poor performance might not be redeemable by future high performance. Such readings put the planned delivery date at risk, and further actions are required.

Even if the project appears to be highly efficient, there might be problems. Efficiency above 1.1, and especially above 1.2, often indicates that the original plan was based on “low ball” estimates. If so, the plan must be revised.

We also watch for dramatic SPIt changes (say, 20% or more) from one period to the next. While such differences are frequently caused by failures in reporting, we have seen cases where the project team made a sudden change in tactics, causing productivity to dive or to soar.

Threshold breaches are another worrisome type of change. Even if the period-over-period change is small, when the SPIt moves into a new efficiency level other than the green zone, you need to take further action.

A series of related SPIt readings indicates a trend. At ProjectFlightDeck, we generally build action plans for schedule correction based on trends, rather than on individual readings. For long-running projects, we require three or more consecutive readings headed in the same direction to mark a trend. For short-term projects, we reduce the required number of consecutive readings.

Whether it is an individual reading or a trend that demands further action, the generic response is the same: identification of potential problems, root-cause analysis, action planning for remediation, and management communication. The urgency of the analysis, extent of remediating actions, and type of communication vary with the efficiency level involved and root causes identified.

In most cases, if the project status is red, the analysis is done immediately. Action plans vary widely but commonly contain rapid, and sometimes extensive, shifts in schedule and staffing. Communications reflect the seriousness of the problem and extent of adjustment required.

For other statuses, the response is essentially the same, but it is moderately paced, involves smaller adjustments, and employs low-key messaging.

Concept: The Schedule Performance Index for time (SPIt) is the ratio between the time earned on a project (i.e., the Earned Schedule—see April 19, 2015 post) and the time actually consumed.

Chart 1

Practice: The SPIt is the ES metric most commonly used to monitor schedule performance. Given that the project is already tracking the amount of schedule earned, the SPIt is easy to calculate. It is equally easy to understand.

The SPIt is a measure of schedule performance efficiency. For starters, it indicates whether or not time is being earned according to plan. Beyond that, it gives us a way to gauge how well or how poorly time is being used on the project.

If the SPIt is either above or below 1.0, time is not being used according to plan. If the SPIt is above 1.0, time is being used more efficiently than planned. If the SPIt is below 1.0, time is being used less efficiently than planned.

Further, we can gauge the efficiency of schedule performance using threshold values for the SPIt. The thresholds mark the boundaries between levels of performance efficiency. Because the SPIt is a ratio, rather than an absolute amount, the thresholds apply equally to projects of all sizes.

To ease communication, ProjectFlightDeck associates a red-yellow-green label with each performance level. The label helps the project team and stakeholders understand the status of schedule performance and the motivation for action plans related to the status.

The specific values we use for thresholds are heuristic, rather than deterministic. That is, we adjust them based on our experience with each project, rather leaving them as fixed limits. We have found that the following values are good starting points.

Table 1

If the SPIt is below .8, we say that schedule performance is very poor and assign a red status. When the SPIt is above .8 but below .9, performance is poor, and we apply a yellow label. If the SPIt is between .9 and 1.0, the performance is allocated a green status. In the green zone, an SPIt of 1.0 (which is not often seen in practice), indicates good performance, exactly aligned with expectations. Otherwise, the performance is considered fair.

Like the fuel efficiency of a car, the SPIt can go above the nominal rating. Although SPIt greater than 1.0 is often viewed positively, it can indicate problems. So, the red-yellow-green labels are also applied to SPIt greater than 1.0.

Table 2

If the SPIt is greater than 1.0 but less than 1.1, performance is very good, and a green status is awarded. If the SPIt is greater than 1.1 but less than 1.2, the performance rating is remarkably high, and a yellow label is assigned. For SPIt greater than 1.2, performance is implausibly high, and the red status applies.

Chart 1 illustrates the application of the thresholds to a recent project.