time_cost = person months spent on fix/refactor/project total including training and any temporary lost efficiency
total_improvement = specific to scenario
payoff_period = time_cost / total_improvement
roi_amount (months) = (total_improvement * roi_period) - time_cost
roi_percent = roi_amount /time_cost
To combine multiple sources of improvement
total_improvement = sum(improvements)
efficiency_loss = fraction of development time lost to technical debt/issues being addressed
percent_improvement = percent reduction in efficiency loss expected to acheived by this fix/refactor/project expressed as fraction/decimal
n = number of developers impacted
roi_period = period over which to evaluate ROI
total_improvement = (efficiency_loss * percent_improvement * n)
value_of_unblocked_PBIs cost_of_unblocking (= time_cost) cost_of_unblocked
total_improvement = value_of_unblocked_PBIs * (cost_of_unblocking / (cost_of_unblocking + cost_of_unblocked))
CPU Time, RAM, HD
User
cost_of_defect = The average cost to business of the likely class of defect chance_of_defect = The chance a defect will happen percent_improvement = The percent reduction in chance of defect happening
risk_of_defect = cost_of_defect * chance_of_defect total_improvement = cost_of_defect * percent_improvement
cost_of_defect = The average cost to business of the likely class of defect expected_number_of_defects = The expected number of defects expected_percent_defect_reduction = The expected number of defects
risk_of_defects = cost_of_defect * expected_number_of_defects total_improvement = risk_of_defects * expected_percent_defect_reduction