Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

[markov_chains_II] to [money_inflation]spelling and example admontion #546

Merged
merged 6 commits into from
Aug 15, 2024
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 12 additions & 2 deletions lectures/markov_chains_II.md
Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,8 @@ that
The stochastic matrix $P$ is called **irreducible** if all states communicate;
that is, if $x$ and $y$ communicate for all $(x, y)$ in $S \times S$.

```{prf:example}
:label: mc2_ex_ir
For example, consider the following transition probabilities for wealth of a
fictitious set of households

Expand All @@ -95,6 +97,7 @@ $$

It's clear from the graph that this stochastic matrix is irreducible: we can eventually
reach any state from any other state.
```

We can also test this using [QuantEcon.py](http://quantecon.org/quantecon-py)'s MarkovChain class

Expand All @@ -107,6 +110,9 @@ mc = qe.MarkovChain(P, ('poor', 'middle', 'rich'))
mc.is_irreducible
```

```{prf:example}
:label: mc2_ex_pf

Here's a more pessimistic scenario in which poor people remain poor forever

```{image} /_static/lecture_specific/markov_chains_II/Irre_2.png
Expand All @@ -116,6 +122,7 @@ Here's a more pessimistic scenario in which poor people remain poor forever

This stochastic matrix is not irreducible since, for example, rich is not
accessible from poor.
```

Let's confirm this

Expand Down Expand Up @@ -272,6 +279,9 @@ In any of these cases, ergodicity will hold.

### Example: a periodic chain

```{prf:example}
:label: mc2_ex_pc

Let's look at the following example with states 0 and 1:

$$
Expand All @@ -291,7 +301,7 @@ The transition graph shows that this model is irreducible.
```

Notice that there is a periodic cycle --- the state cycles between the two states in a regular way.

```
Not surprisingly, this property
is called [periodicity](https://stats.libretexts.org/Bookshelves/Probability_Theory/Probability_Mathematical_Statistics_and_Stochastic_Processes_(Siegrist)/16%3A_Markov_Processes/16.05%3A_Periodicity_of_Discrete-Time_Chains).

Expand Down Expand Up @@ -392,7 +402,7 @@ plt.show()
````{exercise}
:label: mc_ex1

Benhabib el al. {cite}`benhabib_wealth_2019` estimated that the transition matrix for social mobility as the following
Benhabib et al. {cite}`benhabib_wealth_2019` estimated that the transition matrix for social mobility as the following

$$
P:=
Expand Down
6 changes: 4 additions & 2 deletions lectures/mle.md
Original file line number Diff line number Diff line change
Expand Up @@ -39,14 +39,16 @@ $$

where $w$ is wealth.

```{prf:example}
:label: mle_ex_wt

For example, if $a = 0.05$, $b = 0.1$, and $\bar w = 2.5$, this means

* a 5% tax on wealth up to 2.5 and
* a 10% tax on wealth in excess of 2.5.

The unit is 100,000, so $w= 2.5$ means 250,000 dollars.

```
Let's go ahead and define $h$:

```{code-cell} ipython3
Expand Down Expand Up @@ -242,7 +244,7 @@ num = (ln_sample - μ_hat)**2
σ_hat
```

Let's plot the log-normal pdf using the estimated parameters against our sample data.
Let's plot the lognormal pdf using the estimated parameters against our sample data.

```{code-cell} ipython3
dist_lognorm = lognorm(σ_hat, scale = exp(μ_hat))
Expand Down
14 changes: 7 additions & 7 deletions lectures/money_inflation.md
Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ Our model equates the demand for money to the supply at each time $t \geq 0$.
Equality between those demands and supply gives a *dynamic* model in which money supply
and price level *sequences* are simultaneously determined by a set of simultaneous linear equations.

These equations take the form of what are often called vector linear **difference equations**.
These equations take the form of what is often called vector linear **difference equations**.

In this lecture, we'll roll up our sleeves and solve those equations in two different ways.

Expand All @@ -49,19 +49,19 @@ In this lecture we will encounter these concepts from macroeconomics:
* perverse dynamics under rational expectations in which the system converges to the higher stationary inflation tax rate
* a peculiar comparative stationary-state outcome connected with that stationary inflation rate: it asserts that inflation can be *reduced* by running *higher* government deficits, i.e., by raising more resources by printing money.

The same qualitive outcomes prevail in this lecture {doc}`money_inflation_nonlinear` that studies a nonlinear version of the model in this lecture.
The same qualitative outcomes prevail in this lecture {doc}`money_inflation_nonlinear` that studies a nonlinear version of the model in this lecture.

These outcomes set the stage for the analysis to be presented in this lecture {doc}`laffer_adaptive` that studies a nonlinear version of the present model; it assumes a version of "adaptive expectations" instead of rational expectations.

That lecture will show that

* replacing rational expectations with adaptive expectations leaves the two stationary inflation rates unchanged, but that $\ldots$
* it reverse the pervese dynamics by making the *lower* stationary inflation rate the one to which the system typically converges
* it reverses the perverse dynamics by making the *lower* stationary inflation rate the one to which the system typically converges
* a more plausible comparative dynamic outcome emerges in which now inflation can be *reduced* by running *lower* government deficits

This outcome will be used to justify a selection of a stationary inflation rate that underlies the analysis of unpleasant monetarist arithmetic to be studies in this lecture {doc}`unpleasant`.
This outcome will be used to justify a selection of a stationary inflation rate that underlies the analysis of unpleasant monetarist arithmetic to be studied in this lecture {doc}`unpleasant`.

We'll use theses tools from linear algebra:
We'll use these tools from linear algebra:

* matrix multiplication
* matrix inversion
Expand Down Expand Up @@ -349,7 +349,7 @@ g2 = seign(msm.R_l, msm)
print(f'R_l, g_l = {msm.R_l:.4f}, {g2:.4f}')
```

Now let's compute the maximum steady-state amount of seigniorage that could be gathered by printing money and the state state rate of return on money that attains it.
Now let's compute the maximum steady-state amount of seigniorage that could be gathered by printing money and the state-state rate of return on money that attains it.

## Two computation strategies

Expand Down Expand Up @@ -950,7 +950,7 @@ Those dynamics are "perverse" not only in the sense that they imply that the mon


```{note}
The same qualitive outcomes prevail in this lecture {doc}`money_inflation_nonlinear` that studies a nonlinear version of the model in this lecture.
The same qualitative outcomes prevail in this lecture {doc}`money_inflation_nonlinear` that studies a nonlinear version of the model in this lecture.
```


Expand Down
6 changes: 3 additions & 3 deletions lectures/money_inflation_nonlinear.md
Original file line number Diff line number Diff line change
Expand Up @@ -35,14 +35,14 @@ As in that lecture, we discussed these topics:
* an **inflation tax** that a government gathers by printing paper or electronic money
* a dynamic **Laffer curve** in the inflation tax rate that has two stationary equilibria
* perverse dynamics under rational expectations in which the system converges to the higher stationary inflation tax rate
* a peculiar comparative stationary-state analysis connected with that stationary inflation rate that assert that inflation can be *reduced* by running *higher* government deficits
* a peculiar comparative stationary-state analysis connected with that stationary inflation rate that asserts that inflation can be *reduced* by running *higher* government deficits

These outcomes will set the stage for the analysis of {doc}`laffer_adaptive` that studies a version of the present model that uses a version of "adaptive expectations" instead of rational expectations.

That lecture will show that

* replacing rational expectations with adaptive expectations leaves the two stationary inflation rates unchanged, but that $\ldots$
* it reverse the pervese dynamics by making the *lower* stationary inflation rate the one to which the system typically converges
* it reverses the perverse dynamics by making the *lower* stationary inflation rate the one to which the system typically converges
* a more plausible comparative dynamic outcome emerges in which now inflation can be *reduced* by running *lower* government deficits

## The model
Expand Down Expand Up @@ -399,7 +399,7 @@ Those dynamics are "perverse" not only in the sense that they imply that the mon
* the figure indicates that inflation can be *reduced* by running *higher* government deficits, i.e., by raising more resources through printing money.

```{note}
The same qualitive outcomes prevail in {doc}`money_inflation` that studies a linear version of the model in this lecture.
The same qualitative outcomes prevail in {doc}`money_inflation` that studies a linear version of the model in this lecture.
```

We discovered that
Expand Down