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© ThreeCs LimitedCredit Scoring and Credit Control XVI
Pre-conference Workshop
Credit Scoring and Credit Control XVI
Pre-conference Workshop 28/08/19
ImplementationPractical Considerations to Sit Alongside the Theory
David B. EdelmanThreeCs Limited
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Practical Considerations to Sit
Alongside the Theory
• Characteristic Selection– What are the practical considerations we need when selecting which
characteristics to include in the modelling process?
– Model Selection• Which of the same practical considerations apply when selecting which model to use?
• Setting the Scorecard Cut-off– What are some of the options we use in selecting the cut-off?
• Up-Selling– What is this and what are the potential benefits and disadvantages?
• Over-rides– What are these, what are the key things to consider when managing
them, and how to set our over-ride strategy?
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Characteristic Selection• When we select a characteristic for the modelling
process and, therefore, for possible inclusion in the final
model, what are the features that we are looking for in
this characteristic?
• For example, would hair colour be a good characteristic?
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Desirable - Legality
Some characteristics may be very powerful statistically but are not permitted by law or by agreement.
This varies from country to country
Typically,– Gender
– Full-time / part-time employment – correlated with gender
– Race, colour, religion, country of origin, etc.
There are fewer restrictions - once we leave the consumer area, e.g. data protection and discrimination are less of an issue
- once we move from application to behaviour
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Desirable - Stability
Characteristics, attributes and therefore scores are not
subject to cultural or legal changes
Examples:
• Living with Partner – Married / single
• Single after marital breakdown – single / married / divorced?
• Residential Status – tenant / living with partner
• Retired / Unemployed
• Legal Status – sole trader / partnership / lim. co.
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• We want characteristics which, either on their own or in combination with other characteristics, help us to separate along the spectrum of scores,
• the very low risks
• the moderately low risks
• the medium risks
• the high risks
• ... but how do we measure this?
Desirable – Ability to Differentiate
Between Goods and Bads
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Information Value / Power• One measure that we use is the Information Value and Power
• Information value =
• ( (% Good - % Bad) * Ln (% Good / % Bad) )
Power = Information Value * 1000
The higher the power, the more the characteristic, when considered on its own, is able to separate out the cases into different levels of risk.
Rule of Thumb
Power < 50, discard characteristic
50 < Power < 200, discard characteristic unless there is a strong reason to include it in the modelling process
Power > 200, include characteristic in the modelling process, but select one from each group of obviously highly-correlated characteristics
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Desirable - Intuitive Sense
• The characteristics in a scorecard should make sense.
• The score weights attached to the attributes should make directional and relative sense.
• There is no formal test – just an application of some common sense.
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Desirable - Simple to Obtain
We need information that is simple to obtain and reliable.
Characteristic:
• Total £ Credits last 6 months / Total £ Debits last 6 months
• Divided by
• Total £ Credits last 2 months / Total £ Debits last 2 months
Might be very powerful – but how to source the information?
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Characteristic Selection
• Relevance – ability to predict risk – power of characteristic
• Legal
• Stable
• Intuitive
• Simple to Obtain
additionally
• Verifiable
• Clear and Unambiguous
And if the characteristics have these properties, then the model
is a long way to having them as well
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Practical Considerations to Sit
Alongside the Theory
• Characteristic Selection
• Setting the Scorecard Cut-off
• Up-Selling
• Over-rides
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Score
% P
opul
atio
n
Cut-
off
Reject
Rate
Bad
Rate
Scorecard
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The scorecard simply ranks cases in terms of risk.
The business decides where to set the pass mark.
Different businesses have different business models and
operate at different points on the risk spectrum.
Setting the Cut-off – Business Strategy
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Setting Cut-off
• What factors might we use to set the cut-off?
• How do you decide who to accept and who to reject ?
• In behavioural scoring or collections scoring, how do we
decide which treatment to give to which account?
• What thresholds might we apply to these factors?
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What Factors do we Use to Set Application
Scorecard Cut-off’s?
• Acceptance Rate• Bad Rate• Loss• Marginal Bad Rate• Breakeven Position• Maximum volume subject to some constraint
• Profit and Loss of Tranches of Lending• Profit and Loss of Product• Projected Provisions• Balance Sheet Growth
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Strategy Trade-off Table / Run Book
This is a report created to show, for a wide range of cut-
off’s, what will be the impact on:
• Acceptance Rate
• Bad Rate
• Marginal Bad Rate
• Decline Rate for Good accounts
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Strategy Setting
0%
5%
10%
15%
20%
25%
140 160 180 200 220 240 260
ScoreNew Scorecard - Options
Current Scorecard
Use data extracted from the Run Book to consider strategic options
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Cut-off and Business Strategies
• Each position on the curve of the new scorecard represents a
different risk appetite with different consequences for the
operation and the financials of the business.
• As an example, we are going to consider four different, but feasible and rational, options for setting the scorecard cut-off, to help us decide where to set the cut-off.
• Each option has quite different effects on the dynamics of the P&L Account and ultimately on the business’s Balance Sheet.
• We refer to an extract from the Run Book for this scorecard development. This extract reveals the current Rates and Numbers of Accepted Accounts and Bad Accounts.
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Setting the Cut-off - ScenariosA Same acceptance rate
B Same Bad Rate
C a 1/5th reduction in acceptance rate
D Same Value of Losses
For each scenario, we can evaluate the impact on
Acceptance Rate
Number of Good cases
Number of Bad cases
Bad Rate
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Options - Summary
Cut-off Acceptance
Rate
Bad
Rate
# Good’s # Bad’s
A
B
C
D *
Current Scorecard
Acceptance Rate 35.2% Bad Rate 3.91%
= change in # = number of
* We will make a reasonable assumption
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• This scorecard is calibrated so that a score of 200 gives the same acceptance rate as the previous scorecard.
• With the same cut-off and the same Acceptance Rate of 35.2%, we use a better scorecard to remove some Bad Accounts that we took on last time and replace them with some Good Accounts.
• The better scorecard reduces the Bad Rate at the cut-off (or in the 200-204 band) from 9% to 4.54%. This is the Marginal Bad Rate.
• The better scorecard reduces the Bad Rate from 3.91% of all accepted applications to 2.57% of all accepted applications.
• This generates 591 fewer Bad accounts – reduced losses – and also 591 more Good accounts – higher income. These groups of 591 accounts are the “swap sets”.
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Option A – Same Acceptance Rate
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Option B – Same Bad Rate
• Option B uses the fact that the organisation is comfortable with a Bad Rate of 3.91%.
• We can use the better scorecard and accept many more cases. We can do this with a scorecard cut-off of 180. This raises the Marginal Bad Rate at the cut-off from 4.53% to 7.84%, up by more than 70%.
• This generates more Bad Accounts but many more Good accounts.
• Acceptance Rate increases from 35.2% to 52.0%. This generates 2540 Bad accounts, an increase of 820. This also generates an additional 20180 Good accounts.
• This strategy will introduce a much larger scale to the business, with the consequences of that.
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Option C – Reduce Acceptance Rate by 1/5th
• Option C uses an improved credit assessment tool to raise significantly the quality of the book.
• We need an Acceptance Rate of 4/5 * 35.2% = 28.16%.
• We can do this with a scorecard cut-off of 210, giving an Acceptance Rate of 28%.
• This generates fewer Bad Accounts but also fewer Good accounts.
• The Bad Rate falls to 2.11%, and the Acceptance Rate falls from 35.2% to 28.0%
• This generates 737 Bad accounts, a reduction of 983. It also generates a reduction of Good accounts totalling 8017.
• Option C represents a reduction in business but a much higher quality of new business.
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Option D – Same Value of Losses
• Option D assumes that the organisation is comfortable with the existing number of Bad accounts, and the existing losses.
• We shall assume that the average loss on a Bad account is unchanged.*
• Therefore, we need a cut-off that offers c.1720 Bad accounts.
• This is at 190.
• Acceptance Rate increases from 35.2% to 43.2%
• This generates 1719 Bad accounts, the same number of Bad cases but a higher number of Good cases. The Bad Rate falls to 3.18%.
• This generates an additional 10001 Good accounts.
• * If we think that the average loss on a Bad account has increased by 3% or
5%, this can be factored in.
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0%
5%
10%
15%
20%
25%
140 160 180 200 220 240 260
Score
A
A Same Acceptance Rate - Reduced Bad Debt
B Same Bad Debt Rate – Much Higher Acceptance Rate
C Reduced Acceptance Rate – Much Reduced Bad Debt
D Same Bad Debt Value – Higher Acceptance Rate
C
B
D
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Options - SummaryAcceptance Bad Good’s Bad’s
Rate Rate
Current 35.2% 3.91%
A 200 35.2% 2.57% 591 (591)
B 180 52.0% 3.91% 20180 820
C 210 28.0% 2.11% (8017) (983)
D 190 43.2% 3.18% 10001 (1)
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Loss / Expected Loss
• Some organisations use Expected Loss in setting cut-off.
• Expected Loss =
– Probability of Default (PD) * %
– Loss Given Default (LGD) * %
– Exposure at Default (EAD) $ / £ / €
• Many organisations focus on Bad Rates – which will be aligned with PD only
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Loss / Expected LossOne implication from using EL is that … we will accept
some higher PD cases with low LGD.
In a mortgage book, for example, this will mean that we will
take on some higher risk (PD) cases where the LTV is
low and so we are less likely to lose ultimately.
This is really “lending against security” which is against
standard bank lending principles.
It also generates additional work for the collections
department – although it may be “good” work for them as
they can collect / recover much of the sums due.
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Setting the Cut-off – Next Steps• Assess profitability of each option
• Understand constraints – operational, capital, regulatory
• Data and modelling challenges– Profit on a good account and Loss on a bad account
– Profile of future applicant population
– Income from X-selling product v. customer
– time horizon
– accurate knowledge of costs
– quality of earnings – penalty fees - a good source of income?
– amount classified and percentage recovered
– fixed costs apportionment
• Too good for credit
• Getting Executive approval
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Practical Considerations to Sit
Alongside the Theory
• Characteristic Selection
• Setting the Scorecard Cut-off
• Up-Selling
• Over-rides
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Up-Sell – Definition
• Applicant applies for a personal loan of £12000.
• Assessed as satisfactory – pass – accept.
• Affordability assessment suggests that we would lend up to £17000.
• Do we offer (i.e. try to up-sell to) £17000?
• Do we offer (i.e. try to up-sell to) £15000?
• Do we offer (i.e. try to up-sell to) £14000?
• Do we offer only the £12000 the applicant requested?
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Up-Selling
• This is a way for the credit function to support the
business in its drive to higher profits.
• Should we do this?
• What are the advantages and disadvantages?
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There may be a difference between
applicant asking for £12K
applicant asking for £12K but our assessing that they
could afford to borrow £17K and they then borrow £17K
Reputational issue?
Performance difference? - need to record both amounts
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Up-Sell Issues
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Up-Sell Issues
• Pricing
• Higher borrowing may be at lower interest rates.
• TescoBank - pricing from July 2019
• £4800 @ 10.5% 36 months £154.94 per month
• £5200 @ 3.5% 36 months £152.24 per monthBorrow £400 more and it actually costs £97.20 less – a gain of £497!
• Business loss
• An extra loan – to cover sunk marketing and sales costs
• Lower value loan – higher interest rate
• Customer benefit
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Up-Sell Issues
• Sales
• How is increased limit to be sold / communicated?
• What is the process?
• What is the justification?
• Is it affected by what is being purchased?
• Sales incentives on value of sales
• Sales incentive on value of income e.g. value * Interest Rate
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The Moral Dimension
• What would constitute responsible borrowing?
• What would constitute responsible lending?
• A dilemma for Ethics man!
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Practical Considerations to Sit
Alongside the Theory
• Characteristic Selection
• Setting the Scorecard Cut-off
• Up-selling
• Over-rides
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Over-rides
• Definition
• Operational Management
• Strategy
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Over-Rides
• What are they?
• Who sanctions them?
• Recording, managing and tracking over-rides
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Over-rides – what are they?
• Cases where the outcome/decision is contrary to the
scorecard recommendation.
– Recommended “Approve” cases but which are declined –
High Side Over-rides – HSO’s
– Recommended “Decline” cases but which are approved –
Low Side Over-rides – LSO’s
• Both need to be recorded for analysis and tracking
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Low Side Over-rides
• Usually, LSO’s are more problematic than HSO’s
• If approved by underwriters - may be OK
• If approved by branch staff / dealers / brokers –
usually not OK as a process
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Low Side Over-rides
• How do they occur?
• What reasons do people use to try to justify them?
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• Good Customer What is a good customer? Whose definition? Consistency from one operator or member of branch staff to another?
• Profitable Customer Do we know? Do we know accurately? Or are we just making some assumptions, perhaps based on number of products held?
• I don’t understand why it failed While education about the policy and the process should be implemented, it is not the role of the sales operator to understand every decision. Perhaps, we should have a mechanism for them to refer isolated cases.
• We used to accept this type of proposal We have changed our policy because it needed to be changed. Or we may have changed bureau. To over-ride just takes us back to where we were.
• I think we should experiment with this one We can consider experimentation - but it is not the role of the branch staff or dealer to decide on which cases should be included in an experiment.
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• Only failed by a few points If you approve a case failing by 3 points, then next week you will be asked to approve a case failing by 5, and then by 6. This erodes our cut-off decision. Again, perhaps we should have a mechanism for them to refer isolated cases.
• Value of connection How do we measure this? It is true that declining the application may jeopardize the relationship. However, it can work in the other direction. Granting a child a loan may annoy the parent.
• Cross-subsidisation How do we identify which product(s) are actually subsidising which?
• I need it to reach my sales target Even if we have sympathy with this, why should we allow them to over-ride the case at 5 p.m. on a Friday? There is almost certainly a case much more deserving, closer to the cut-off, that was declined earlier in the week / month.
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Potentially Acceptable Reasons
• Controlled and planned experimentation with cut-off
and/or policy
• Underwriter selection of anomalous good cases
among declines using Additional Data Not available
to the scorecard
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Low Side Over-rides
• Need recording and tracking
• Should be managed as normal
• May tell us something about our process - especially
if they perform well
• Can we amend credit criteria and take them on in the
normal course of events?
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Beware of Cherry-Picking
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
<200 200-219 220-239 240-259 260-279 280-299 300+
Score
Bad
Dev
Sample 1
Sample 2
Sample 3
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Portfolio 1: Age < 30
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10%
20%
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50%
60%
0 - 529 530 -
539
540 -
549
550 -
559
560 -
569
570 -
579
580 -
589
590 -
599
600 -
609
610 -
619
620 -
629
630 +
0
1000
2000
3000
4000
5000
6000
Volume Bad Rate Predicted Bad Rate
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Cherry-Picking
LSO’s may be subject to cherry-picking or very careful selection
If so, we would not want to take on all cases, for example, in the
scoreband below the current cut-off.
This may be for reasons of:
• Risk
• Processing
• Business objectives
Much better - try to identify the rules of the cherry-pickers and
implement these into the system.
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High-Side Over-Rides
How do these occur?
• Operational checks implemented after the scorecard:
– credit policy
– verification checks, e.g. Money Laundering, Matching at Bureau
• Underwriter Caution or inability to deal with new types of risks or
inability to price accordingly
• The applicant has an existing account with the bank in arrears
• The organisation has had a bad credit experience with the
applicant
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HSO’s
Usually represent less of an issue – as they are “only” a
lost opportunity rather than an actual exposure.
We don’t know how they would have performed.
Cases which pass the scorecard cut-off and are
rejected will, on average, be of lower quality than
those which pass and are accepted … but
would they have been profitable?
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Over-Ride Analysis
For the HSO’s we do not know how they would have
performed. We have another reject inference problem.
Analysis:
• Try to understand why they were rejected.
• Accept a sample of them and see how they perform.
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Over-Ride’s – Some Strategy Options
Through analysis, develop our strategy for if and when
we allow over-rides.
Over-
rides OK
LSO’s
only
HSO’s only
within15
points of
cut-off
HSO’s
only for
certain
reasons
No Over-
rides
Volume
Bad Rate
# Bad’s
Profit
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Over-rides - Summary
• Overrides should be processed through a credit / underwriting / review process.
• Manual processing costs increase when overrides are in place.
• We need to extract value from this additional cost.
• Over-rides should not generally be subject to “special handling”
• Over-rides should be tracked and analysed.
• Over-rides generate uncertainty when analysing alternative strategies.
• We should try to control the over-ride percentages.
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Practical Considerations to Sit
Alongside the Theory
• Characteristic Selection
• Setting the Scorecard Cut-off
• Up-Selling
• Over-rides
Enjoy the Conference
David B. Edelman
ThreeCs Limited
Credit Scoring and Credit Control XVI
Pre-conference Workshop