Variance is the difference between a planned value and the actual value that occurred: a step planned for 8 hours that took 10 has a variance of plus 2 hours. It applies to dates, hours, pieces, and cost. Variance does not just flag that a job drifted off plan; it says by how much and in which direction, which is what a planner needs to fix the next plan.
EDGEBIC by User Solutions tracks variance across dates, hours, and cost, and surfaces it on its earned value and on-time reports. This article defines the term and shows how the product keeps the comparison honest.
How It Works
Every variance is a subtraction: planned minus actual, or actual minus planned, depending on which sign convention makes an overrun positive. The plan side comes from the scheduling engine at the time the job was committed. The actual side comes from the shop floor, captured as real start dates, end dates, hours worked, and pieces produced.
The value of variance depends entirely on referencing a stable plan. If the planned figure kept changing every time you rescheduled, the comparison would be meaningless, because you would always be measuring reality against your latest guess. That is why the original planned dates are frozen at first scheduling and never overwritten. A job can be rescheduled a dozen times, but its original start and end dates remain, so completion-date variance always measures against the date you first committed to.
A Concrete Example
Take one milling step. The plan, set when the job was scheduled, calls for 8 hours of work starting Monday at 8 a.m. and finishing Monday at 4 p.m. The floor logs the reality: the operator started Monday at 8:30 a.m. and finished the step at 6 p.m., logging 9 hours of actual work.
The variances fall out directly. Start-date variance is 30 minutes late. Completion-date variance is 2 hours late against the frozen 4 p.m. plan. Hours variance is plus 1 hour, an unfavorable overrun. If the work center's rate is known, that extra hour also produces a cost variance. None of these is a judgment on the operator; together they say the milling estimate for this product runs about an hour light, which is a concrete thing to correct.
How EDGEBIC Uses It
Variance flows from the actuals pipeline. As operators record start dates, end dates, and hours against each step, those actual values sit next to the planned values that were frozen at scheduling time. The difference is variance, and it appears on the earned value report and the on-time report, broken down by date, hours, and cost.
Because the original planned dates are never moved by a reschedule and completed work is never re-planned, the variance you see is always measured against the honest baseline. That makes the number trustworthy enough to act on: a consistent unfavorable hours variance on one work center points straight at a planning estimate that needs correcting, rather than leaving you to pad every job blindly.
Variance is the raw input to the earned value story. It feeds directly into earned value and the performance indexes that summarize whether a job is ahead or behind on time and cost. The manufacturing glossary covers the related reporting terms, and schedule adherence explains the process discipline that low variance reflects.
Expert Q&A: Deep Dive
Q: Every job seems to run over its planned hours, but I cannot tell whether it is one bad work center or the whole shop. How do I find out?
A: Look at hours variance broken down by work center rather than by job. Variance is planned minus actual, and when you aggregate it per resource a pattern usually jumps out: one station consistently runs plus 20 percent while the rest track close to plan. That tells you the planning time on that station is wrong, not that the whole shop is slow. In EDGEBIC the actuals captured from the floor sit against the frozen planned baseline, so the variance on each work center is honest, and correcting that one estimate does more for accuracy than a blanket padding of every job.
Q: Why keep the original planned dates around after a job has been rescheduled ten times?
A: Because without the frozen original, variance loses its meaning. If every reschedule overwrote the plan, the schedule would always look on target, since you would be comparing actuals against the most recent guess rather than the commitment you made. EDGEBIC freezes the original start and end dates at first scheduling and never overwrites them, so completion-date variance always measures against what you first promised. That is what lets you say honestly whether a job that shipped Tuesday was early, on time, or late against the date it was actually committed to weeks earlier.
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