Let me declare today that I have a new enemy -
Cost Accounting.
In 1981, at a conference of Management Accountants, Eliyahu Goldratt declared Cost Accounting to be "Enemy #1 of Productivity". In my work as a consultant for
ThoughtWorks, I value productivity highly. Hence the enemy of my friend is also my enemy.
Goldratt, author of the popular business novel "
The Goal", showed how traditional cost accounting easily and trivially leads intelligent managers and other decision makers to make bad decisions - decisions that have massive negative effects on performance and profitability. This was actually not surprising news, as the problems with cost accounting had been recognised. But Goldratt also proposed an alternative.
His alternative was titled "
Throughput Accounting", and was described in the 1998
book by Thomas Corbett. It is an accounting model which does not focus primarily on local cost optimisation and instead focuses primarily on overall system throughput. Importantly, it does not attempt to allocate overhead costs across products and services.
Why is this important? Cost accounting attempts to allocate a companies fixed costs over a given time period to the products or services produced in that period. It enables managers to ignore the fixed costs and focus instead on the results of each period in relation to the products produced. This made sense in the 1890s, when cost accounting was developed, as most companies had extremely low fixed costs. The majority of costs were labour, which at the time was fully variable, as workers were only paid for the hours they laboured at the demand of the employer. Although there was distortion due to the overhead allocation, it was extremely small.
Modern businesses, however, have a much lower proportion of fully variable costs. Most costs are fixed, especially labour as now most employees work fixed hours regardless of demand. Due to this environmental change, the distortion caused by cost allocation is much larger and can cause management decisions, based on cost accounting, that directly result in large loses of productivity and profit.
As an example, imagine a company has fixed overheads of $10,000 (plant and labour) per month and currently produces 800 widgets with a materials cost of $40. The unit cost per widget would be $52.50 ($40 + $10,000/800). If an order now came for an additional 500 widgets at a price of $50, then management based on cost accounting should reject the order as it would result in a loss of $2.50 per widget. However, as the majority of costs are fixed, the increase in production would actually result in a new unit cost of $47.69 ($40 + $10,000/1300), so profits would actually increase by $1,153.85. This might seem clear, but imagine this example with many different products and prices in the mix and quickly it becomes hard to see the mistake. This is
only one example of a poor decision made due to a cost accounting metric.
So why am I so concerned? In the software industry, especially, there is very little variable costs. The overwhelming expense is for developers, which are typically in short supply, so they are not a variable cost. Basing our decisions around software projects and the ROI from software delivery on cost accounting can lead to incredibly poor outcomes.
In future blog posts, I'll also explore what I believe is another critically important aspect of Throughput Accounting - the focus on throughput and inventory reduction over costs. I believe this has the potential for a massive effect on the software delivery process, especially when combined with the Lean practices that
ThoughtWorks is pursuing in the industry.
Believe me when I say this -
Throughput Accounting will become of major importance in our industry. It will make a dramatic change to the way we finance software projects and it has the power to put real numbers around why we use
Agile and
Lean principles and practices (as shown in David Andersons book "
Agile Management for Software Engineering").
If your interested in another good introductory text, in addition to
Corbetts book, try the
book by Steven Bratt, also titled "Throughput Accounting".