Cost control is central to project plan execution. It follows status collection and plan variance analysis in the project tracking cycle. It is necessary in any cycle where you discover a significant cost or effort variance, or your earned value management measurements are out of limit. For each variance, review its root cause and impact on the project timeline. Determine whether the impact is a one-time or short-term issue, or whether the root cause is a longer term—a chronic problem or part of an adverse trend.