Skip to main content
What-if analysis shows how adjustments to your financial plan affect your success probability. Drift runs sensitivity tests and generates personalized scenarios based on your spending patterns.

​
How What-If Analysis Works

After your base simulation, Drift automatically:
  1. Runs sensitivity tests on key variables (income, spending, timeline)
  2. Identifies high-impact changes that improve success probability
  3. Generates specific scenarios targeting your largest discretionary spending categories
  4. Provides implementation tips for each scenario
All what-if scenarios run the same 100,000 Monte Carlo simulations as your base case - only the input parameters change.

​
Sensitivity Table

The sensitivity table compares your current plan against alternative scenarios: Screenshot description: Table with 6 rows showing:
ScenarioChangeProbabilityImpact
Current plan-65%-
Cut Food & Dining-50% (~225/mofrom225/mo from 450/mo)73%🟢 +8%
Reduce total spending by 10%-10% total spending71%🟢 +6%
Extend timeline by 6 months+6 months78%🟢 +13%
Increase income+$500/mo (7.7% raise)72%🟢 +7%
Balance cuts across categoriesDining, Shopping, Entertainment70%🟢 +5%

​
Reading the Table

1

Current Plan Row

The first row (highlighted) shows your baseline success probability with no changes.
2

Scenario Descriptions

Each row describes a specific change to test. Drift prioritizes actionable, realistic adjustments.
3

New Probability

The “Probability” column shows success rate if you implement this change.
4

Impact Badge

The “Impact” column shows the improvement (green ↑) or decline (red ↓) vs. your current plan.
  • High impact: +10% or more → Prioritize this change
  • Medium impact: +5-10% → Meaningful improvement
  • Low impact: Less than 5% → Marginal benefit

​
Automated Scenario Generation

Drift analyzes your spending categories and generates three types of scenarios:

​
1. Category-Specific Cuts

Targets your largest discretionary spending category: 
// From whatIfService.ts
const nonEssential = categories.filter(([name]) => {
  const lower = name.toLowerCase()
  return ['dining', 'restaurant', 'entertainment', 'shopping', 
          'travel', 'subscription', 'coffee', 'bar'].some(k => 
    lower.includes(k)
  )
})

const [name, monthlyAmount] = nonEssential[0]  // Largest category
const cutPercent = Math.min(0.5, gap / monthlyAmount)  // Up to 50%
Example Output:

Reduce Food & Dining

Change: Cut Food & Dining by 50% (save 225/mofrom225/mo from 450/mo)New Success Probability: 73% (↑ +8%)Implementation Tips:
  • Cook at home 4-5 times per week
  • Pack lunch for work instead of buying
  • Meal prep on Sundays for the week
  • Use grocery delivery instead of restaurants

​
2. Balanced Multi-Category Cuts

Spreads reductions across your top 3 discretionary categories: 
// From whatIfService.ts
const top3 = nonEssential.slice(0, 3)
const cutPerCategory = gap / top3.length

top3.forEach(([name, amount]) => {
  const cutPercent = Math.min(0.3, cutPerCategory / amount)  // Max 30% each
  newSpending[name] = (amount * (1 - cutPercent)) * 12
})
Example Output:

Balance Cuts Across Categories

Change: Reduce Dining, Shopping, Entertainment to save $250/mo totalNew Success Probability: 70% (↑ +5%)Implementation Tips:
  • Identify your most flexible categories
  • Set specific spending limits
  • Track weekly spending
  • Build in occasional treats to stay motivated

​
3. Income Increase

Shows impact of earning more through raises or side income: 
// From whatIfService.ts
const incomeIncrease = gap / 10  // Conservative estimate
modifiedRequest.userInputs.monthlyIncome += incomeIncrease

const percentIncrease = (incomeIncrease / baseRequest.userInputs.monthlyIncome) * 100
Example Output:

Increase Income

Change: Earn $250/mo more (3.8% raise or side income)New Success Probability: 72% (↑ +7%)Implementation Tips:
  • Ask for a raise or promotion
  • Develop side hustle (5-10 hrs/week)
  • Freelance in your skill area
  • Negotiate better salary at next job

​
Standard Sensitivity Tests

Drift also runs these standardized tests:
Test: What if total spending changes by 10%?
// Reduce spending by 10%
modifiedRequest.financialProfile.monthlySpending *= 0.9

// Increase spending by 10%
modifiedRequest.financialProfile.monthlySpending *= 1.1
Typical Results:
  • -10% spending: +5-8% success probability
  • +10% spending: -5-8% success probability
Use Case: Quick estimate of how lifestyle changes affect goals

​
High-Impact Moves

The results page highlights the top 2 highest-impact scenarios: Screenshot description: Two cards with green glowing borders: Card 1:
  • Extend timeline by 6 months | 🟢 +13%
  • “+6 months”
Card 2:
  • Cut Food & Dining | 🟢 +8%
  • “50% (~225/mofrom225/mo from 450/mo)”
// From Sensitivity.tsx
const topActions = combinedScenarios
  .sort((a, b) => Math.abs(b.impact) - Math.abs(a.impact))
  .slice(0, 2)
Focus on the top 2 scenarios first. Implementing both can compound their effects.

​
Category-Specific Implementation Tips

Drift provides tailored advice based on the spending category:

​
Food & Dining

// From whatIfService.ts - getTips()
if (lower.includes('dining') || lower.includes('restaurant')) {
  return [
    'Cook at home 4-5 times per week',
    'Pack lunch for work instead of buying',
    'Meal prep on Sundays for the week',
    'Use grocery delivery instead of restaurants',
  ]
}

​
Entertainment & Shopping

if (lower.includes('entertainment') || lower.includes('shopping')) {
  return [
    'Unsubscribe from unused streaming services',
    'Cancel unnecessary subscriptions',
    'Set a weekly shopping budget',
    'Use 30-day rule for non-essentials',
  ]
}

​
Travel

if (lower.includes('travel')) {
  return [
    'Plan trips during off-season',
    'Use rewards points and miles',
    'Travel locally more often',
    'Split accommodations with friends',
  ]
}

​
Generic Tips

// Default for other categories
return [
  'Track spending in this category weekly',
  'Set a specific budget limit',
  'Find alternatives or substitutes',
  'Gradually reduce over time',
]

​
Alternative Strategies Card

If your median outcome falls short of the goal, Drift displays an “Alternative Strategies” card on the results page: Screenshot description: Card titled “Alternative Strategies” with subtitle “Ways to improve your success probability”. Three expandable scenario cards below showing:
  1. Reduce Food & Dining: 65% → 73% (🟢 +8%)
    • Monthly savings: $225
    • Tips: Cook at home 4-5x/week, pack lunch, meal prep
  2. Balance cuts across categories: 65% → 70% (🟢 +5%)
    • Monthly savings: $250
    • Tips: Set limits, track weekly, build in treats
  3. Increase income: 65% → 72% (🟢 +7%)
    • Monthly increase needed: $250
    • Tips: Ask for raise, side hustle, freelance
// From WhatIf.tsx
const shortfall = Math.max(0, goalAmount - medianOutcome)

if (shortfall > 0) {
  fetch('/api/whatif/scenarios', {
    method: 'POST',
    body: JSON.stringify({
      request: { financialProfile, userInputs, goal },
      currentSuccessProbability,
      gap: shortfall,
    })
  })
}

​
Combining Multiple Changes

Drift simulates one change at a time, but you can manually combine strategies:

​
Example: Stacking Improvements

Base Case: 65% success probability, $2,500 shortfall Strategy 1: Cut dining by 50% → +8% = 73% Strategy 2: Extend timeline by 6 months → +13% = 78% Combined (estimate): Both changes → +18-20% = ~83-85%
Combined effects are not perfectly additive due to interaction effects, but they generally compound positively.

​
How to Test Combined Scenarios

1

Implement First Change

Update your profile (e.g., reduce spending category)
2

Adjust Goal

Update timeline or target amount
3

Rerun Simulation

Generate new results with both changes applied
4

Compare

Check if combined success probability meets your target (75%+)

​
Interpreting Negative Scenarios

Some scenarios show declining success probability:
Example Negative Scenarios:
  • Increase spending by 10%: 65% → 57% (🔴 -8%)
  • Reduce income by 10%: 65% → 55% (🔴 -10%)
  • Shorten timeline by 6 months: 65% → 48% (🔴 -17%)
Use Cases:
  • Model worst-case scenarios (job loss, unexpected expenses)
  • Understand sensitivity to negative events
  • Build contingency plans

​
Recommendations

Drift generates natural language recommendations based on sensitivity results: 
// From simulationService.ts - runSensitivityAnalysis()
if (sensitivities['spending_minus_10'].impact > 0.05) {
  recommendations.push(
    'Reducing spending by 10% could significantly improve your odds.'
  )
}

if (sensitivities['income_plus_10'].impact > 0.05) {
  recommendations.push(
    'Increasing income (side gig, raise) would have high impact.'
  )
}

if (sensitivities['timeline_plus_6mo'].impact > 0.05) {
  recommendations.push(
    'Extending your timeline by 6 months gives more room for growth.'
  )
}
Screenshot description: Recommendation list:
  • “Extending your timeline by 6 months gives more room for growth.”
  • “Reducing spending by 10% could significantly improve your odds.”
  • “Increasing income (side gig, raise) would have high impact.”

​
Custom Scenario Testing

Advanced users can test custom scenarios by editing their profile:

​
Example: Test 20% Spending Reduction

1

Navigate to Dashboard

View your current financial profile
2

Adjust Spending

Manually reduce spending estimates:
  • Current: $4,200/mo
  • Test: $3,360/mo (-20%)
3

Rerun Simulation

Start a new simulation with adjusted profile
4

Compare Results

Check new success probability vs. baseline
Manual adjustments override Plaid data. Revert to actual spending after testing scenarios.

​
Most Impactful Variables (Ranked)

Based on typical simulations, here’s the average impact:
1

Timeline Extension (Highest Impact)

+6 months: +10-15% success probabilityWhy: More time = more contributions + more compoundingBest for: Flexible goals where timing isn’t critical
2

Spending Reduction

-10%: +5-8% success probabilityWhy: Increases monthly savings directlyBest for: Goals with discretionary spending room
3

Income Increase

+10%: +6-10% success probabilityWhy: Boosts savings rate without lifestyle changesBest for: Career professionals with raise potential
4

Goal Amount Reduction (Last Resort)

-10%: +8-12% success probabilityWhy: Lower bar to success, but compromises original intentBest for: When timeline/spending/income can’t change

​
Next Steps

Interpreting Results

Understand the base simulation metrics before exploring scenarios

Setting Goals

Refine your goal based on what-if insights
Action Plan Template:
  1. Identify highest-impact scenario (+10% or more)
  2. Implement changes gradually (20% per month)
  3. Track actual spending vs. targets
  4. Rerun simulation quarterly to verify progress
  5. Adjust as needed based on real results

Build docs developers (and LLMs) love

Get started for freeTalk to us