Investment Multiplier, Income Gaps & Thrift
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Multiplier initial autonomous spending से repeated income–consumption rounds का total income effect बताता है। Calculation से पहले पहचानें: question income effect माँग रहा है या required initial spending? दोनों answers अलग हैं।
Simple Investment Multiplier
Two-sector, fixed-price model में autonomous investment change का total effect।
Worked example: MPC = 0.75 → k = 4; ΔI = 50 → ΔY = 200।
Interpretation: 50 initial injection है; 200 total income increase, जिसमें initial injection included है।
Required Autonomous Injection
Given income gap को भरने के लिए initial expenditure कितना बढ़ाना है?
Worked example: Current Y* = 800, full-employment Yf = 1000, k = 4 → required injection = 200/4 = 50।
Interpretation: Income gap 200 को directly expenditure gap न मानें।
| Round | Income/spending generated: initial 100, MPC 0.75 |
|---|---|
| Initial | 100 |
| First induced round | 75 |
| Next rounds | 56.25, 42.1875, … |
| Total geometric limit | 100/(1−0.75) = 400 |
- Assumptions: autonomous injection, constant MPC, spare capacity/fixed prices, no added tax/import leakages in this simple formula, no offsetting fall in other spending।
- Higher MPS → smaller multiplier; contractionary autonomous change produces multiplied income fall too।
- Paradox of thrift: all households simultaneously attempt more saving through lower consumption; with I fixed and idle capacity, Y can fall so aggregate saving at equilibrium stays equal to fixed I। It is not a universal claim that saving is harmful।
- At full capacity extra nominal demand may raise prices rather than real output; simple multiplier cannot be applied mechanically there।
Active Recall / Writing Practice
- MPC = 0.8, income gap = 300 से required injection निकालें।
- Paradox of thrift में planned और realised saving का difference लिखें।
Notes बन्द करके लिखें। Review: next day, third day और seventh day. Notes delivery और mastery अलग हैं।
Memory recap: Income effect = injection × k; required injection = income gap ÷ k।
Topic Test · 12 MCQs
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Your Revision Result
Your answer: · Correct answer: C. 5
k=1/(1−.8)=1/.2=5।
Your answer: · Correct answer: C. ₹160
k=1/.25=4; ΔY=4×40=160।
Your answer: · Correct answer: C. k=5; MPC=0.8
k=300/60=5; MPS=1/5=.2; MPC=.8।
Your answer: · Correct answer: A. ₹75
k=4; required injection=income gap/k=300/4=75।
Your answer: · Correct answer: C. ₹30 और ₹125
First induced spending=.6×50=30; total=50/(1−.6)=125, including initial50।
Your answer: · Correct answer: A. −₹80
Multiplier4 है; ΔY=4×(−20)=−80। Contraction भी multiplied होती है।
Your answer: · Correct answer: B. 5 से 4
k=1/MPS; old5 और new4। Higher leakage propensity multiplier घटाती है।
Your answer: · Correct answer: D. ΔY −₹80; equilibrium saving unchanged
Autonomous spending −20 से Y−80। Fixed I के कारण new planned equilibrium saving भी same I के बराबर है: thrift paradox case।
Your answer: · Correct answer: C. ₹50
ΔI=ΔY/k=200/4=50। Income effect और initial spending को अलग रखें।
Your answer: · Correct answer: D. Extra demand prices बढ़ा सकती है; real output proportionately नहीं
Real multiplier को spare capacity/fixed-price assumptions चाहिए; capacity constraint price response पैदा कर सकती है।
Your answer: · Correct answer: C. ₹180
k=1/.5=2; total ΔY=2×90=180।
Your answer: · Correct answer: B. ₹180
Initial100 + first induced80=180। ₹500 all-round geometric total है, two-round sum नहीं।
Numerical routine: identify concept → select formula → substitute → interpret. Wrong/guessed/slow items को 24 hours बाद फिर solve करें।