The Limits of Choice

Wann und warum sparen private Haushalte? Sahra Wagenknecht untersucht in ihrer Dissertation den Zusammenhang von Sparentscheidungen und Grundbedürfnissen in Deutschland und den USA von den 1950er-Jahren bis heute. Ihre zentrale Hypothese lautet, dass der Einkommensanteil der Ausgaben zur Befriedigung von Grundbedürfnissen die entscheidende Erklärungsvariable des individuellen Sparverhaltens darstellt. In Abgrenzung zur Lebenszyklus- bzw. Permanenten Einkommenshypothese (LCPIH) kann Wagenknecht zeigen, dass die individuelle Sparquote entscheidend vom langfristigen Einkommen abhängt. Die Arbeit weist für einen Zeitraum von über 50 Jahren nach, dass sich auch auf volkswirtschaftlicher Ebene die Veränderung der privaten Sparquote durch den "necessity share" erklären lässt. Das vorgelegte Modell liefert zudem eine Erklärung, weshalb die private Sparquote bei steigender Einkommensungleichheit in Volkswirtschaften mit dereguliertem Kreditmarkt sinkt, während sie bei restriktiven Kreditmärkten steigt.

Sahra Wagenknecht ist promovierte Volkswirtin, Publizistin und Politikerin, seit Oktober 2015 Vorsitzende der Linksfraktion im Deutschen Bundestag. Von 2010 bis 2014 war sie Stellvertretende Parteivorsitzende, von 2004 bis 2009 Abgeordnete im Europäischen Parlament.

Contents
List of Figures 11
List of Variables and Abbreviations 13
Introduction 19
Chapter 1. Stylised Facts of Saving
Paragraph 1.1 Data Sets and Statistical Issues 33
1.1.1 Various Saving Aggregates and Their Relationship 33
1.1.2 Macroeconomic Data Sources for the U.S. and Germany 34
1.1.3 Measurement Problems - Saving Offshore or Saving Out of Realised Capital Gains 36
1.1.4 Statistical Revisions 37
1.1.5 Microeconomic Data Sources for the U.S. and Germany 38
Paragraph 1.2 The Historic Path of Saving 40
1.2.1 General Trends in the OECD 40
1.2.2 Saving in the U.S. and its Various Components 40
1.2.3 Saving in Germany and its Various Components 44
Paragraph 1.3 Stylised Facts at the Macroeconomic Level 47
1.3.1 Real Income 47
1.3.2 Growth 49
1.3.3 Real Interest Rates 51
1.3.4 Inflation 52
1.3.5 Unemployment and Social Security Standards 54
1.3.6 Demographics 55
1.3.7 Inequality 55
1.3.8 Institutional Environment 58
1.3.9 Persistency 59
Paragraph 1.4 Stylised Facts at the Microeconomic Level 60
1.4.1 Macroeconomic Facts and Microeconomic Distributions 60
1.4.2 Saving Rates in Cross-Section 61
1.4.3 Current Income, Real and Relative 64
1.4.4 Permanent Income 72
1.4.5 The Distribution of Financial Wealth 74
1.4.6 Growth, Income Fluctuations and the Role of Expectations 79
1.4.7 Uncertainty and Precautionary Saving 83
1.4.8 Life-Cycle Patterns of Saving 85
1.4.9 Saving Motives 87
Paragraph 1.5 Summary: Stylised Facts of Saving 89
Chapter 2. Do Standard Models of Saving Match the Facts?
Paragraph 2.1 The Standard LCPIH 93
2.1.1 Basic Ideas of the Standard Approach 93
2.1.2 The Modigliani-Diagram 94
2.1.3 The Perfect Foresight Model in Discrete Time 97
2.1.4 The Perfect Foresight Model in Continuous Time 101
2.1.5 The Certainty Equivalent Model 104
Paragraph 2.2 The Empirical Failure of the Standard Models 108
2.2.1 Excess Sensitivity and Excess Smoothness - Ambiguous Results 108
2.2.2 MPC and Income Growth - Wrong Predictions 109
2.2.3 Incapability to Explain Saving Rate Differentials 110
Paragraph 2.3 Refinements: Allowing for Precautionary Saving, Liquidity Constraints and Habit Formation 112
2.3.1 Convex Marginal Utility and the Precautionary Motive 112
2.3.2 The Technique of Stochastic Dynamic Programming 113
2.3.3 The Buffer-Stock Model 116
2.3.4 Liquidity Constrained Consumers 120
2.3.5 Models Including Habit Formation 121
Paragraph 2.4 Do the Elaborated Models Perform Better? 125
2.4.1 Gain in Realism at the Cost of Predictive Power 125
2.4.2 Remaining Deficiencies 126
Paragraph 2.5 The Optimal Consumption Path - General Remarks 128
2.5.1 Hidden Assumptions and Fundamental Flaws 128
2.5.2 Arguments of the Utility Function - Wealth as an End in Itself 129
2.5.3 A Realistic Time-Horizon 131
2.5.4 The Representative Consumer 132
2.5.5 Per-period Consumption as a Single Entity 138
2.5.6 The Elasticity of Intertemporal Substitution 141
2.5.7 The Optimising Procedure - Benefits and Costs 145
Chapter 3. A New Approach to Saving Behaviour
Paragraph 3.1 Basic Needs and Saving 151
3.1.1 The Relative-Income Hypothesis 151
3.1.2 Subsistence Consumption in Developing Countries 152
3.1.3 Necessities in Developed Countries 156
Paragraph 3.2. Basic Needs in Standard Models 159
3.2.1 Introducing Good-specific Subsistence Points into a Standard Dixit-Stiglitz framework 159
3.2.2 Intertemporal Optimisation with Moving Subsistence Consumption 171
Paragraph 3.3 Modelling Saving Decisions by a Simple Rule of Thumb 178
3.3.1 The Necessity Share in Outlay and in Income 180
3.3.2 Determinants of Saving under the Proposed Rule of Thumb 181
3.3.3 The Aggregated Saving Rate under the Given Rule of Thumb 184
3.3.4 Factors Influencing the Propensity to Save and to Dissave 191
3.3.5 Summary: Model Predictions 192
Chapter 4. The Patterns of Consumption Shares
Paragraph 4.1 How to Identify Basic Needs? 197
4.1.