vamseeachanta Price / Volume Decomposition (+3)
Price / Volume Decomposition
The most fundamental variance decomposition. Used for revenue, cost of goods, and any metric that can be expressed as Price x Volume.
Formula:
Total Variance = Actual - Budget (or Prior)
Volume Effect = (Actual Volume - Budget Volume) x Budget Price
Price Effect = (Actual Price - Budget Price) x Actual Volume
Mix Effect = Residual (interaction term), or allocated proportionally
Verification: Volume Effect + Price Effect = Total Variance
(when mix is embedded in the price/volume terms)
Three-way decomposition (separating mix):
Volume Effect = (Actual Volume - Budget Volume) x Budget Price x Budget Mix
Price Effect = (Actual Price - Budget Price) x Budget Volume x Actual Mix
Mix Effect = Budget Price x Budget Volume x (Actual Mix - Budget Mix)
Example — Revenue variance:
- Budget: 10,000 units at $50 = $500,000
- Actual: 11,000 units at $48 = $528,000
- Total variance: +$28,000 favorable
- Volume effect: +1,000 units x $50 = +$50,000 (favorable — sold more units)
- Price effect: -$2 x 11,000 units = -$22,000 (unfavorable — lower ASP)
- Net: +$28,000
Rate / Mix Decomposition
Used when analyzing blended rates across segments with different unit economics.
Formula:
Rate Effect = Sum of (Actual Volume_i x (Actual Rate_i - Budget Rate_i))
Mix Effect = Sum of (Budget Rate_i x (Actual Volume_i - Expected Volume_i at Budget Mix))
Example — Gross margin variance:
- Product A: 60% margin, Product B: 40% margin
- Budget mix: 50% A, 50% B → Blended margin 50%
- Actual mix: 40% A, 60% B → Blended margin 48%
- Mix effect explains 2pp of margin compression
Headcount / Compensation Decomposition
Used for analyzing payroll and people-cost variances.
Total Comp Variance = Actual Compensation - Budget Compensation
Decompose into:
1. Headcount variance = (Actual HC - Budget HC) x Budget Avg Comp
2. Rate variance = (Actual Avg Comp - Budget Avg Comp) x Budget HC
3. Mix variance = Difference due to level/department mix shift
4. Timing variance = Hiring earlier/later than planned (partial-period effect)
5. Attrition impact = Savings from unplanned departures (partially offset by backfill costs)
Spend Category Decomposition
Used for operating expense analysis when price/volume is not applicable.
Total OpEx Variance = Actual OpEx - Budget OpEx
Decompose by:
1. Headcount-driven costs (salaries, benefits, payroll taxes, recruiting)
2. Volume-driven costs (hosting, transaction fees, commissions, shipping)
3. Discretionary spend (travel, events, professional services, marketing programs)
4. Contractual/fixed costs (rent, insurance, software licenses, subscriptions)
5. One-time / non-recurring (severance, legal settlements, write-offs, project costs)
6. Timing / phasing (spend shifted between periods vs plan)