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The Theory of Chains

The Theory of Chains

The Theory of Chains presents some basic concepts in efficiency, effectiveness and process improvement, with a dash of humor.

For more, read "The Goal" by Eliyahu M. Goldratt, and search for "the theory of constraints"

Scott Wlaschin

March 15, 2014
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  1. The Theory of Chains Some (possibly overly simplistic but hopefully

    not too condescending) stories to help us think about what we are here for…
  2. The fable of the two mules Let’s start with the

    famous fable of two mules who were tied together.
  3. The fable of the two mules They each wanted grass,

    but neither could get any because they were pulling in opposite directions.
  4. For anyone who doesn’t know this story... The moral is

    that co-operation is better than struggle. The fable of the two mules
  5. But that’s not my moral... The fable of the two

    mules For anyone who doesn’t know this story... The moral is that co-operation is better than struggle.
  6. Efficiency vs. Effectiveness Die Slowly Die Quickly Ineffective Effective Efficient

    Inefficient A helpful and un-ironic four-quadrant diagram
  7. Efficiency vs. Effectiveness Die Slowly Die Quickly Ineffective Effective Efficient

    Inefficient A helpful and un-ironic four-quadrant diagram
  8. Efficiency vs. Effectiveness Thrive Die Slowly Survive Die Quickly Ineffective

    Effective Efficient Inefficient A helpful and un-ironic four-quadrant diagram
  9. Efficiency vs. Effectiveness “Efficiency is doing things right; effectiveness is

    doing the right things.” “There is surely nothing quite so useless as doing with great efficiency what should not be done at all.” “The most serious mistakes are not being made as a result of wrong answers. The true dangerous thing is asking the wrong question.” -- Peter Drucker.
  10. The chain I replaced my steel with aluminium I reduced

    my diameter by 2mm A more efficient chain!
  11. The chain We cut costs by 10% We were 15%

    more efficient We saved £100K Fulfilment IT Sales Finance ??? A more efficient business!
  12. The chain We cut costs by 10% We were 15%

    more efficient We saved £100K Fulfilment IT Sales Finance ??? A more efficient business!
  13. The chain Me too! I’ll lend you some of my

    metal There is no point making other links efficient until the weakest link is strengthened.. Help the weakest link get stronger.
  14. The chain • What is the goal of a chain?

    • Is there always a weakest link?
  15. The chain • What is the goal of a chain?

    • Is there always a weakest link? Yes!
  16. The chain • What is the goal of a chain?

    • Is there always a weakest link? • What is the most effective action to take?
  17. The chain • What is the goal of a chain?

    • Is there always a weakest link? • What is the most effective action to take? Make the weakest link stronger
  18. The bucket brigade Water input Water output ... if Mr

    Blue is faster than Mr Pink? A big puddle coming soon.
  19. The bucket brigade Water input Water output ... if Mr

    Green is faster than Mr Pink? Mr Green does a lot of waiting. He is quite bored now. Even Twitter has lost its charm.
  20. The bucket brigade Water input Water output • What is

    the goal of a bucket brigade? To move as much water as possible in as little time as possible. Throughput, not efficiency.
  21. The bucket brigade Water input Water output • What is

    the goal of a bucket brigade? • What (or rather who) determines the throughput?
  22. The bucket brigade Water input Water output • What is

    the goal of a bucket brigade? • What (or rather who) determines the throughput? The slowest person
  23. The bucket brigade Water input Water output • What is

    the goal of a bucket brigade? • What (or rather who) determines the throughput? • Is there always a weakest link?
  24. The bucket brigade Water input Water output • What is

    the goal of a bucket brigade? • What (or rather who) determines the throughput? • Is there always a weakest link? Yes! There is always a slowest person
  25. The bucket brigade Water input Water output • What is

    the goal of a bucket brigade? • What (or rather who) determines the throughput? • Is there always a weakest link? • What is the most effective action to take?
  26. The bucket brigade Water input Water output • What is

    the goal of a bucket brigade? • What (or rather who) determines the throughput? • Is there always a weakest link? • What is the most effective action to take? Make the weakest link stronger
  27. The bucket brigade Water input Water output • What is

    the goal of a bucket brigade? • What (or rather who) determines the throughput? • Is there always a weakest link? • What is the most effective action to take? Make the weakest link stronger Make the slowest person faster
  28. The bucket brigade Water input Water output Question: Which person

    never gets a rest? What happens if he does rest?
  29. The bucket brigade Water input Water output Question: Which person

    never gets a rest? What happens if he does rest? Hint
  30. The bucket brigade Water input Water output Question: Which people

    always get a chance to be idle? What happens if you insist that they always keep working?
  31. The bucket brigade Water input Water output Question: Which people

    always get a chance to be idle? What happens if you insist that they always keep working? Hint
  32. How a business works Our business Stuff we buy Stuff

    we sell Inventory/Investment Operating expenses
  33. The goal of a business Inventory/Investment Operating expenses Our business

    Throughput These numbers are related, often in unobvious ways. Changing one affects all the others. It’s a balancing act!
  34. The goal of a business Inventory/Investment Operating expenses Our business

    Throughput Some common metrics to help you relate the numbers and do the balancing act...
  35. The goal of a business Inventory/Investment Operating expenses Our business

    Throughput Net profit (NP) = Throughput (T) - Operating expense (OE) Some common metrics to help you relate the numbers and do the balancing act...
  36. The goal of a business Inventory/Investment Operating expenses Our business

    Throughput Return on investment (ROI) = Net profit (NP) ÷ Investment (I) Some common metrics to help you relate the numbers and do the balancing act...
  37. The goal of a business Inventory/Investment Operating expenses Our business

    Throughput Productivity = Throughput (T) ÷ Operating Expense (OE) Some common metrics to help you relate the numbers and do the balancing act...
  38. The goal of a business Inventory/Investment Operating expenses Our business

    Throughput Investment Turns = Throughput (T) ÷ Investment (I) Some common metrics to help you relate the numbers and do the balancing act...
  39. What if a bucket brigade was like a business? Another

    overly-simplistic business analogy....
  40. If the bucket brigade were a business... Water input Water

    output If the bucket brigade were a business, what questions would we ask?
  41. If the bucket brigade were a business... Water input Water

    output What is the throughput? How long does it take a bucket to move through the system (“flow time”)? a.k.a "latency"
  42. If the bucket brigade were a business... Water input Water

    output What is the throughput? How long does it take a bucket to move through the system (“flow time”)? What is the current inventory?
  43. If the bucket brigade were a business... Water input Water

    output What is the throughput? How long does it take a bucket to move through the system (“flow time”)? What is the current inventory? What are the operating expenses?
  44. Real Numbers Mr Pink can do 1 Bucket/hour Mr Blue

    can do 2 Buckets/hour Mr Green can do 3 Buckets/hour Let’s look at some real numbers! Each bucket sells for a markup of $24 Each worker costs $12/hour
  45. Real Numbers 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour What is

    the throughput? $12/hour $24 $24 $24 $24 $12/hour $12/hour
  46. Real Numbers 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour What is

    the throughput? $12/hour $24 $24 $24 $24 $12/hour $12/hour 1 bucket/hour (Mr Pink is to blame)
  47. Real Numbers 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour What is

    the throughput? How long does it take a bucket to move through the system (“flow time”)? $12/hour $24 $24 $24 $24 $12/hour $12/hour
  48. Real Numbers 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour What is

    the throughput? How long does it take a bucket to move through the system (“flow time”)? $12/hour $24 $24 $24 $24 $12/hour $12/hour Mr Blue takes 30 min per bucket, and Mr Green takes 20 min, so it takes a bucket 1h 50m to go through the system.
  49. Real Numbers 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour What is

    the throughput? How long does it take a bucket to move through the system (“flow time”)? What is the current inventory? $12/hour $24 $24 $24 $24 $12/hour $12/hour
  50. Real Numbers 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour What is

    the throughput? How long does it take a bucket to move through the system (“flow time”)? What is the current inventory? $12/hour $24 $24 $24 $24 $12/hour $12/hour Little’s law: inventory = throughput * flow time. So inventory = 1 bucket/hour x 1.83 hours => 1.83 buckets
  51. Real Numbers 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour What is

    the throughput? How long does it take a bucket to move through the system (“flow time”)? What is the current inventory? What are the operating expenses? $12/hour $24 $24 $24 $24 $12/hour $12/hour
  52. Real Numbers What is the throughput? How long does it

    take a bucket to move through the system (“flow time”)? What is the current inventory? What are the operating expenses? 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $12/hour $12/hour $12/hour x three people = $36/hour
  53. Real Numbers Throughput (buckets/hr) (money/hr) Flow time Inventory (buckets) Opex

    (money/hr) Net Profit (money/hr) = T - OE Inventory turns = T/I 1/hr or $24/hr 1h 50m 1.83 $36/hr -$12/hr 0.54 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $12/hour $12/hour Here are all the numbers.... Oh noes.... We’re losing money!
  54. Real Numbers We’re losing money – what should we do?

    Let’s step back and look at the problem...
  55. Real Numbers We’re losing money – what should we do?

    Let’s step back and look at the problem... Mr Pink is working flat out but look at all the idle people! Mr Blue is only working ½ time. And Mr Green is working only a third of the time. Lazy sod!
  56. Real Numbers We’re losing money – what should we do?

    Let’s step back and look at the problem... Mr Pink is working flat out but look at all the idle people! Mr Blue is only working ½ time. And Mr Green is working only a third of the time. There’s your problem right there!
  57. Real Numbers What to do? Option 1: Panic! Option 1:

    Reduce wages or staff (helps with operating expenses) Especially the lazy ones like Mr Pink...
  58. Real Numbers What to do? Option 1: Reduce wages or

    staff (helps with operating expenses) Option 2: Hire extra people (helps with throughput, maybe?)
  59. Real Numbers What to do? Option 1: Reduce wages or

    staff (helps with operating expenses) Option 2: Hire extra people (helps with throughput, maybe?) Option 3: Change the process (but how?)
  60. Fixing the problem by reducing staff Let’s start with option

    1: “Reduce staff on the non-bottlenecks” 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $12/hour $12/hour A.k.a. Don’t pay people to be idle.
  61. Fixing the problem by reducing staff As it happens, around

    this time, Mr Blue had a very unfortunate industrial accident – he was cut in half.
  62. Fixing the problem by reducing staff As it happens, around

    this time, Mr Blue had a very unfortunate industrial accident – he was cut in half. Luckily he can still work at 2 buckets/hour, But since there is only half of him, his average throughput is now 1 bucket/hr.
  63. Fixing the problem by reducing staff As it happens, around

    this time, Mr Blue had a very unfortunate industrial accident – he was cut in half. Luckily he can still work at 2 buckets/hour, But since there is only half of him, his average throughput is now 1 bucket/hr. As a result, the cruel capitalists who employ him have decided to slash his salary in half as well -- to only $6/hr.
  64. Fixing the problem by reducing staff By coincidence Mr Green

    also had a very unfortunate industrial accident – he was cut into one third.
  65. Fixing the problem by reducing staff By coincidence Mr Green

    also had a very unfortunate industrial accident – he was cut into one third.
  66. Fixing the problem by reducing staff By coincidence Mr Green

    also had a very unfortunate industrial accident – he was cut into one third. His productivity is only a third now. Just like Mr Blue, his average is now 1 bucket/hr. The cruel capitalists have decided to slash his salary even more -- to only $4/hr.
  67. Fixing the problem by reducing staff Here is the new

    setup. Mr Blue and Mr Green have been rehired at lower wages, corresponding to their lower throughput. 1 Bucket/hour 1 Bucket/hour 1 Bucket/hour $6/hour $24 $24 $24 $24 $12/hour $4/hour
  68. Fixing the problem by reducing staff What is the throughput?

    Still 1 bucket/hour 1 Bucket/hour 1 Bucket/hour 1 Bucket/hour $6/hour $24 $24 $24 $24 $12/hour $4/hour
  69. Fixing the problem by reducing staff What is the throughput?

    How long does it take a bucket to move through the system (“flow time”)? Mr Blue and Mr Green have lower throughputs, but their latency is still the same. so the flow time is unchanged at 1h 50min. 1 Bucket/hour 1 Bucket/hour 1 Bucket/hour $6/hour $24 $24 $24 $24 $12/hour $4/hour
  70. Fixing the problem by reducing staff What is the throughput?

    How long does it take a bucket to move through the system (“flow time”)? What is the current inventory? Same as before. 1 Bucket/hour 1 Bucket/hour 1 Bucket/hour $6/hour $24 $24 $24 $24 $12/hour $4/hour
  71. Fixing the problem by reducing staff What is the throughput?

    How long does it take a bucket to move through the system (“flow time”)? What is the current inventory? What are the operating expenses? $6 + $12 + $4 = $22/hour 1 Bucket/hour 1 Bucket/hour 1 Bucket/hour $6/hour $24 $24 $24 $24 $12/hour $4/hour
  72. Fixing the problem by reducing staff Throughput (buckets/hr) (money/hr) Flow

    time Inventory (buckets) Opex (money/hr) Net Profit (money/hr) = T - OE Inventory turns = T/I 1/hr or $24/hr 1h 50m 1.83 $22/hr +$2/hr 0.54 Here are the new numbers... 1 Bucket/hour 1 Bucket/hour 1 Bucket/hour $6/hour $24 $24 $24 $24 $12/hour $4/hour
  73. Fixing the problem by adding staff Now try option 2:

    “Adding extra staff on the bottleneck” That is -- bring the weakest links up to speed 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $12/hour $12/hour
  74. Fixing the problem by adding staff We’ll hire 2 people

    to help Mr Pink. This team’s throughput is now 3 buckets/hour! 3 Buckets/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $36/hour $12/hour
  75. Fixing the problem by adding staff But now Mr Blue

    is the bottleneck. 3 Buckets/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $36/hour $12/hour
  76. Fixing the problem by adding staff But now Mr Blue

    is the bottleneck. Luckily he has a half-brother who can help. 3 Buckets/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $36/hour $12/hour
  77. Fixing the problem by adding staff But now Mr Blue

    is the bottleneck. Luckily he has a half-brother who can help. Literally! 3 Buckets/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $36/hour $12/hour
  78. Fixing the problem by adding staff Mr Blue’s throughput is

    now 3 buckets/hour as well. 3 Buckets/hour 3 Buckets/hour 3 Buckets/hour $18/hour $24 $24 $24 $24 $36/hour $12/hour
  79. Fixing the problem by adding staff Throughput (buckets/hr) (money/hr) Flow

    time Inventory (buckets) Opex (money/hr) Net Profit (money/hr) = T - OE Inventory turns = T/I 3/hr or $72/hr 1h 50m 5.5 $66/hr +$6/hr 0.54 Here are the numbers for this approach. 3 Buckets/hour 3 Buckets/hour 3 Buckets/hour $18/hour $24 $24 $24 $24 $36/hour $12/hour
  80. Fixing the problem by adding staff Moral: Adding staff can

    be more profitable than reducing staff – if you know where to add them. Adding also gives economies of scale, because there are other fixed costs like buildings, etc., which don’t need to be scaled at the same rate.
  81. Fixing the problem by adding staff Moral: Adding staff can

    be more profitable than reducing staff – if you know where to add them. Adding also gives economies of scale, because there are other fixed costs like buildings, etc., which don’t need to be scaled at the same rate. Question: Under what circumstances can you NOT add staff?
  82. Fixing the problem by adding staff Moral: Adding staff can

    be more profitable than reducing staff – if you know where to add them. Adding also gives economies of scale, because there are other fixed costs like buildings, etc., which don’t need to be scaled at the same rate. But can we do even better?
  83. Fixing the problem by changing the process Option 3 is

    “changing the process”. What does that look like? 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24 $24 $12/hour $12/hour
  84. 1 Bucket/hour 2 Buckets/hour 3 Buckets/hour $12/hour $24 $24 $24

    $24 $12/hour $12/hour Fixing the problem by changing the process What happens if we get rid of the second step in the process and merge it into the first?
  85. Fixing the problem by changing the process What happens if

    we get rid of the second step in the process and merge it into the first?
  86. Fixing the problem by changing the process Mr Blue and

    Mr Pink now work together on step 1. Their combined throughput is now 3 buckets/hour.
  87. Fixing the problem by changing the process Mr Blue and

    Mr Pink now work together on step 1. Their combined throughput is now 3 buckets/hour. $12/hour $24 $24 $24 $12/hour 3 Buckets/hour 3 Buckets/hour $12/hour
  88. Fixing the problem by changing the process Mr Blue and

    Mr Pink now work together on step 1. Their combined throughput is now 3 buckets/hour. $12/hour $24 $24 $24 $12/hour 3 Buckets/hour 3 Buckets/hour $12/hour
  89. Fixing the problem by changing the process What is the

    throughput? 3 buckets/hour $12/hour $24 $24 $24 $12/hour 3 Buckets/hour 3 Buckets/hour $12/hour
  90. Fixing the problem by changing the process What is the

    throughput? How long does it take a bucket to move through the system (“flow time”)? Mr Blue and Mr Pink have a combined latency of 40 mins so the total flow time is now 1 hour. $12/hour $24 $24 $24 $12/hour 3 Buckets/hour 3 Buckets/hour $12/hour
  91. Fixing the problem by changing the process What is the

    throughput? How long does it take a bucket to move through the system (“flow time”)? What is the current inventory? Little’s law: inventory = throughput * flow time. So inventory = 3 bucket/hour x 1 hours => 3 buckets $12/hour $24 $24 $24 $12/hour 3 Buckets/hour 3 Buckets/hour $12/hour
  92. Fixing the problem by changing the process What is the

    throughput? How long does it take a bucket to move through the system (“flow time”)? What is the current inventory? What are the operating expenses? $12 x three = $36/hour $12/hour $24 $24 $24 $12/hour 3 Buckets/hour 3 Buckets/hour $12/hour
  93. Fixing the problem by changing the process Throughput (buckets/hr) (money/hr)

    Flow time Inventory (buckets) Opex (money/hr) Net Profit (money/hr) = T - OE Inventory turns = T/I 3/hr or $72/hr 1h 3 $36/hr +$36/hr 1 $12/hour $24 $24 $24 $12/hour 3 Buckets/hour 3 Buckets/hour $12/hour
  94. Summary of different approaches Option Throughput (buckets/hr) (money/hr) Flow time

    Inventory (buckets) Opex (money/hr) Net Profit (money/hr) = T - OE Inventory turns = T/I Original 1/hr or £24/hr 1h 50m 1.83 £36/hr -£12/hr 0.54 Reduce Staff 1/hr or £24/hr 1h 50m 1.83 £22/hr +£2/hr 0.54 Increase Staff 3/hr or £72/hr 1h 50m 5.5 £66/hr +£6/hr 0.54 Change Process 3/hr or £72/hr 1h 3 £36/hr +£36/hr 1.0
  95. Summary of different approaches Option Throughput (buckets/hr) (money/hr) Flow time

    Inventory (buckets) Opex (money/hr) Net Profit (money/hr) = T - OE Inventory turns = T/I Original 1/hr or £24/hr 1h 50m 1.83 £36/hr -£12/hr 0.54 Reduce Staff 1/hr or £24/hr 1h 50m 1.83 £22/hr +£2/hr 0.54 Increase Staff 3/hr or £72/hr 1h 50m 5.5 £66/hr +£6/hr 0.54 Change Process 3/hr or £72/hr 1h 3 £36/hr +£36/hr 1.0
  96. Summary of different approaches Moral: Changing the process can have

    much greater impact than just tweaking efficiencies.
  97. Summary of different approaches Moral: Changing the process can have

    much greater impact than just tweaking efficiencies.
  98. Summary of different approaches Moral: Changing the process can have

    much greater impact than just tweaking efficiencies.
  99. What is the goal of IT? Sales IT Supply Chain

    What is the most effective action for IT to take?
  100. What is the goal of IT? Sales IT Supply Chain

    IT should not be a cost centre
  101. What is the goal of IT? Inventory/Investment Operating expenses The

    business Throughput IT should add value to the business
  102. What is the goal of IT? Inventory/Investment Operating expenses The

    business Throughput IT should add value to the business
  103. What is the goal of IT? Inventory/Investment Operating expenses The

    business Throughput IT should add value to the business
  104. What is the goal of your team? Sales Your team

    Supply Chain What is the most effective action for your team to take?
  105. What is the goal of your team? Inventory/Investment Operating expenses

    The business Throughput Where can your team add value to the business?
  106. What is the goal of your team? Inventory/Investment Operating expenses

    The business Throughput Where can your team add value to the business?
  107. What is the goal of your team? For example, how

    might an HR team add value? How can HR help throughput? • Reduce purchase costs by hiring or training expert purchasers. • Better throughput by encouraging employee feedback and learning. • Promoting and managing continuous improvement. How can HR help capex? - Reduce need for facilities by helping people work remotely. How can HR help opex? • Reduce turnover with better working conditions, training, employee morale.
  108. What is the goal of your team? For example, how

    might an HR team add value? How can HR help throughput? • Reduce purchase costs by hiring or training expert purchasers. • Better throughput by encouraging employee feedback and learning. • Promoting and managing continuous improvement. How can HR help capex? - Reduce need for facilities by helping people work remotely. How can HR help opex? • Reduce turnover with better working conditions, training, employee morale.
  109. What next? “The Goal” by Eliyahu M. Goldratt & Jeff

    Cox And find out about • Value Streams • The “Theory Of Chains” • Lean Enterprise/Lean Accounting • The Toyota Way
  110. What next? “The Goal” by Eliyahu M. Goldratt & Jeff

    Cox And find out about • Value Streams • The “Theory Of Chains” • Lean Enterprise/Lean Accounting • The Toyota Way