From ee9cce3bcb5da4efe0c753f507425624896777f1 Mon Sep 17 00:00:00 2001 From: thomassargent30 Date: Tue, 6 Feb 2024 07:08:49 +0800 Subject: [PATCH] Tom's Feb 6 morning edits of cons_smooth lecture --- lectures/cons_smooth.md | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/lectures/cons_smooth.md b/lectures/cons_smooth.md index 0c92a27e..29d6e2a7 100644 --- a/lectures/cons_smooth.md +++ b/lectures/cons_smooth.md @@ -24,9 +24,9 @@ In this lecture, we'll study what is often called the "consumption-smoothing mo Formulas presented in {doc}`present value formulas` are at the core of the consumption smoothing model because we shall use them to define a consumer's "human wealth". The key idea that inspired Milton Friedman was that a person's non-financial income, i.e., his or -her wages from working, could be viewed as a dividend stream from that person's ``human capital'' +her wages from working, could be viewed as a dividend stream from that person's ''human capital'' and that standard asset-pricing formulas could be applied to compute a person's -``non-financial wealth'' that capitalizes the earnings stream. +''non-financial wealth'' that capitalizes the earnings stream. ```{note} As we'll see in this quantecon lecture {doc}`equalizing difference model `, @@ -345,11 +345,11 @@ print('Welfare:', welfare(cs_model, c_seq)) ### Experiments -In this section we experiment consumption smoothing behavior under different setups. +In this section we decribe how a consumption sequence would optimally respond to different sequences sequences of non-financial income. -First we write a function `plot_cs` that generate graphs above based on a consumption smoothing model `cs_model`. +First we create a function `plot_cs` that generate graphs for different instances of the consumption smoothing model `cs_model`. -This helps us repeat the steps shown above +This will help us avoid rewriting code to plot outcomes for different non-financial income sequences. ```{code-cell} ipython3 def plot_cs(model, # consumption smoothing model @@ -375,6 +375,8 @@ def plot_cs(model, # consumption smoothing model plt.show() ``` +In the experiments below, please study how consumption and financial asset sequences vary accross different sequences for non-financial income. + #### Experiment 1: one-time gain/loss We first assume a one-time windfall of $W_0$ in year 21 of the income sequence $y$. @@ -382,24 +384,24 @@ We first assume a one-time windfall of $W_0$ in year 21 of the income sequence $ We'll make $W_0$ big - positive to indicate a one-time windfall, and negative to indicate a one-time "disaster". ```{code-cell} ipython3 -# Windfall W_0 = 20 +# Windfall W_0 = 2.5 y_seq_pos = np.concatenate( - [np.ones(21), np.array([20]), np.ones(44)]) + [np.ones(21), np.array([2.5]), np.ones(44)]) plot_cs(cs_model, a0, y_seq_pos) ``` ```{code-cell} ipython3 -# Disaster W_0 = -20 +# Disaster W_0 = -2.5 y_seq_neg = np.concatenate( - [np.ones(21), np.array([-20]), np.ones(44)]) + [np.ones(21), np.array([-2.5]), np.ones(44)]) plot_cs(cs_model, a0, y_seq_neg) ``` #### Experiment 2: permanent wage gain/loss -Now we assume a permanent increase in income of $W$ in year 21 of the $y$-sequence. +Now we assume a **permanent** increase in income of $W$ in year 21 of the $y$-sequence. Again we can study positive and negative cases @@ -466,7 +468,7 @@ plot_cs(cs_model, a0, y_seq_geo) What happens when $\lambda$ is negative ```{code-cell} ipython3 -λ = -0.05 +λ = -0.95 geo_seq = λ ** np.arange(t_max) * y_0 y_seq_geo = np.concatenate(