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# Bamboo Weekly #84: Central banks
- URL: https://www.bambooweekly.com/bw-84-central-banks/
- Published: 2024-09-18T15:00:51.000Z
- Updated: 2026-09-19T06:00:04.000Z
- Description: Get better at: Dates and times, grouping, pivot tables, handling missing data, and strings
- Author: Reuven M. Lerner
- Tags: datetime, grouping, pivot-table, missing-data, strings

Inflation is coming down around the world, and central banks are lowering interest rates accordingly. The most important central bank, the US Federal Reserve, is expected to announce the first reduction in interest rates in four years. Today's Washington Post says that experts are divided on whether it'll be a standard quarter-point change, or if they'll go all out with a half-point change ([https://www.washingtonpost.com/business/2024/09/18/fed-rate-cut-fomc/](https://www.washingtonpost.com/business/2024/09/18/fed-rate-cut-fomc/?ref=bambooweekly.com)).

Central bank interest rates affect just about everything in the economy. When they're higher, money costs more. It costs more to take out a mortgage or car loan, so people delay buying houses and cars, or buy smaller ones. It costs more for a business to borrow money, so they make smaller investments. Sounds like that would slow down the economy, right? Indeed, that's precisely the point; raising interest rates is one way to slow the economy, and thus reduce inflation. Once inflation is (mostly) beat, we can lower interest rates again. Which is precisely where things seem to stand now in the US.

This week, we'll look at interest rates at central banks around the world. The data comes from the Bank of International Settlements (BIS, [http://bis.org/](http://bis.org/?ref=bambooweekly.com)), a sort of central bank for central banks. We'll see what rates are, what they were, and how they're changing.

### Data and six questions

The data, as I mentioned, comes from BIS, which supplies quite a bit of data. Go to their data site, at

[https://data.bis.org/topics/CBPOL/data](https://data.bis.org/topics/CBPOL/data?ref=bambooweekly.com)

and click on "export." You can choose to download the data in CSV from

[https://data.bis.org/static/bulk/WS\_CBPOL\_csv\_col.zip](https://data.bis.org/static/bulk/WS%5FCBPOL%5Fcsv%5Fcol.zip?ref=bambooweekly.com)

Or you can click on "code snippet," getting Pandas code that will allow you to download the data, via the BIS API, into Pandas. I would actually recommend against this last option, just because I found that downloading multiple times in a row will result in your computer not being able to download any more; they seem to have some sort of limiting system.

***\[Note: I got something wrong with the above URLs and instructions. I'm not quite sure what, but I've put the file that I intended for you to download at*** [***https://files.lerner.co.il/central-bank-data.csv.zip***](https://files.lerner.co.il/central-bank-data.csv.zip?ref=bambooweekly.com) ***.My apologies!\]***

I have six tasks/questions for you this week. The learning goals include working with dates, grouping, pivot tables, handling missing data, and string handling, among others. I'll be back tomorrow, as usual, with my solutions and Jupyter notebook. Meanwhile, here are my questions:

- Create a data frame from the BIS data. Keep only the rows in which `TIME_PERIOD` has two `-` characters. Turn the remaining values in `TIME_PERIOD` into `datetime` values, and then keep only those rows starting in the year 2000.
- What is the latest interest rate for each central bank? Which five banks have the highest interest rates in the world, and which have the lowest?
- Create a table in which each row represents the last day in each month, each column represents a central bank, and each data cell represents the highest rate during that month.
- Use the data from question 3 to plot reserve-bank rates for the US, Canada, European Central Bank, India, China, and Japan. Which central bank has consistently had the lowest rates? Which has had the highest? What major rises and falls across banks do we see?
- Calculate the month-over-month change in interest rates for each central bank.  
Were there any months in which a majority of banks all lowered their rates from the previous month?
- The US Federal Reserve is considered the most influential central bank in the world. When it raises or lowers rates, other banks consider doing so, too. Calculate the correlation between the rise or drop in Fed rates and those in other central banks, delayed by 2 months. Which five banks move most consistently with the Fed, but with a two-month delay?

I'll be back tomorrow with my full solutions, including the Jupyter notebook I used to calculate my solutions.

Until then,

Reuven