Istvan Hajnal
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istvanhajnal.bsky.social
Istvan Hajnal
@istvanhajnal.bsky.social
58 followers 160 following 69 posts
Statistics, data science, market research, Elvis Costello, bass,
Ipsos, media research, audience measurement.
Boutersem-Amsterdam
Posts Replies Media Videos
Reposted by Istvan Hajnal
istvanhajnal.bsky.social
Het verbaast me dat journalisten en academici Raoul Hedebouw hiermee gewoon laten wegkomen. In @deafspraaktv mocht Hedebouw, beweren dat “we” twee tot zes keer meer uitgeven aan wapens dan de Russen (zie fragment [link.mp4]) #RaoulHedebouw #PVDA #deafspraak #deafspraakopvrijdag #Rusland /1
November 16, 2025 at 12:09 PM
istvanhajnal.bsky.social
Het verbaast me dat journalisten en academici Raoul Hedebouw hiermee gewoon laten wegkomen. In @deafspraaktv mocht Hedebouw, beweren dat “we” twee tot zes keer meer uitgeven aan wapens dan de Russen (zie fragment [link.mp4]) #RaoulHedebouw #PVDA #deafspraak #deafspraakopvrijdag #Rusland /1
November 16, 2025 at 12:09 PM
Reposted by Istvan Hajnal
ivelasq3.bsky.social
Woo, the post is on Data Elixir! It's a really great data science newsletter if you are looking for one!

dataelixir.com
November 12, 2025 at 9:58 PM
istvanhajnal.bsky.social
I wrote a blogpost on clustering respondents within households, and how you can derive a simple rule of thumb for estimating the effect that has on standard errors.
open.substack.com/pub/istvanha...

#DataScience #Statistics #Survey #Methodology
A Back-of-the-Envelope Calculation of the Effect of Clustering Respondents Within Households on Standard Errors
Imagine you’re in a meeting and need to quickly explain how clustering respondents within households affects the length of a confidence interval, but you don’t have a computer handy.
open.substack.com
November 7, 2025 at 2:31 PM
Reposted by Istvan Hajnal
istvanhajnal.bsky.social
I wrote a short LinkedIn article about the Law of Truely Large Numbers (not to be confused with the law of large numbers), Bart De Wever and Ordinal variables.

Enjoy!

lnkd.in/ehKjiFmS

#DataScience #Politics #BDW #Belgium
October 29, 2025 at 2:31 PM
istvanhajnal.bsky.social
I wrote a short LinkedIn article about the Law of Truely Large Numbers (not to be confused with the law of large numbers), Bart De Wever and Ordinal variables.

Enjoy!

lnkd.in/ehKjiFmS

#DataScience #Politics #BDW #Belgium
October 29, 2025 at 2:31 PM
Reposted by Istvan Hajnal
datavisfriendly.bsky.social
#TodayinHistory #dataviz #OTD 📊
💀Oct 25, 1914 Wilhelm Lexis died in Gottingen, Germany 🇩🇪

1875: The Lexis diagram, showing relations among age (cohort), calendar time, and life spans of individuals simultaneously.
Revolutionized demography, making key variables visible
Diagram showing the idea behind the lexis diagram. A grid of Age by Year showing diagonals of Cohort Schematic diagram of a Lexis Diagram. Y axis is Age, X is calendar year. A blue diagonal gives the cohort of people born in a given year over time Black/white photo of Wilhelm Lexis
October 26, 2025 at 1:36 AM
Reposted by Istvan Hajnal
tylermw.com
ggplot(data, aes(x,y)) +
geom_jitter(velocity = units(17000, "mph"))

help, my data is stuck in LEO

#RStats #ggplot #dataviz
November 12, 2024 at 3:41 PM
istvanhajnal.bsky.social
Niet echt verrassend, al maakt deze visualisatie het wel heel zichtbaar: het electoraat van #Ecolo-#Groen en #VlaamsBelang is op leeftijd, inkomensdeciel, cultureel en economisch links-rechts bijna elkaars spiegelbeeld.
#DeStemming #DS2025 #WorkInProgress
October 5, 2025 at 1:16 PM
istvanhajnal.bsky.social
There seems to be no effect of age on perceived suitability of Bart De Wever as Prime Minister in function of age, until about 50, after that there's a strong positive effect (this is a 0-10 point scale).
#DeStemming #BartDeWever #DataScience #WorkInProgress
October 4, 2025 at 3:43 PM
Reposted by Istvan Hajnal
petersagal.bsky.social
I have lived and worked in and around Chicago for 27 years and I have been assaulted less often than Sen Paul has been in his own back yard.
atrupar.com Aaron Rupar @atrupar.com · Sep 28
Rand Paul: "Chicago is a nightmare. It is literally a war zone."
September 28, 2025 at 8:26 PM
istvanhajnal.bsky.social
www.yahoo.com/news/article...
Leading Harvard statistician exits US amid brain drain trend
Liu Jun, one of the world’s leading statisticians and a Harvard University professor since 2000, has left the U.S. to join Tsinghua University in Beijing. Liu was born and raised on the Tsinghua Univ...
www.yahoo.com
September 14, 2025 at 7:26 AM
istvanhajnal.bsky.social
Ben geen grote fan van De Wever, maar een zwak leider is hij allerminst. Mijn sympathie voor hem stijgt zowaar.

#DeWever #Netanyahu #Israel #Gaza
September 3, 2025 at 3:20 PM
Reposted by Istvan Hajnal
alexselbyb.bsky.social
I have a slide about an unusual data request I once got: can we show that song choruses are appearing earlier due to the economics of streaming (gotta hook people in early to get paid)? I joked that it's not as if anyone's got a database of song structures. But it turns out that someone has...
An example of unusual data gathering - Compromise! To listen to the weekly Top 40 from the past 20 years would take 96 days and nights Just the No.1 singles would take 17 hours Listening until the first chorus should only take 5 hours So we listened… and got our chart
August 17, 2025 at 1:37 PM
istvanhajnal.bsky.social
1/
An optimist and a pessimist walk into a bar... and get roped into a 3-question quiz by a statistician. Closest guesses to the truth win.

#datascience #statistics #rstats #mrx #stein #shrinkage
July 28, 2025 at 10:41 AM
Reposted by Istvan Hajnal
istvanhajnal.bsky.social
1/
Een optimist en een pessimist gaan naar een café ... en worden door een statisticus uitgenodigd voor een 3 vragen tellende quiz. Wie het dichtst bij het juiste antwoord zit, wint.

#datascience #statistiek
July 25, 2025 at 2:11 PM
istvanhajnal.bsky.social
1/
Een optimist en een pessimist gaan naar een café ... en worden door een statisticus uitgenodigd voor een 3 vragen tellende quiz. Wie het dichtst bij het juiste antwoord zit, wint.

#datascience #statistiek
July 25, 2025 at 2:11 PM
Reposted by Istvan Hajnal
istvanhajnal.bsky.social
My latest blogpost on #substack: istvanhajnal.substack.com/p/the-kalman...

#datascience #mrx #kalmanfilters #statistics #rstats
The Kalman Filter, Lizards, and Market Research
Imagine you’re a biologist studying the movement of desert lizards.
istvanhajnal.substack.com
July 19, 2025 at 6:35 PM
Reposted by Istvan Hajnal
akjackson.bsky.social
I approve. 8-)
ajackson.quarto.pub/website/Blog...
Cleaning GPS data for Trash Tracker
Tracking Litter using a phone app, and mapping the results. This bit is for cleaning up the GPS data.
ajackson.quarto.pub
July 19, 2025 at 8:08 PM
istvanhajnal.bsky.social
My latest blogpost on #substack: istvanhajnal.substack.com/p/the-kalman...

#datascience #mrx #kalmanfilters #statistics #rstats
The Kalman Filter, Lizards, and Market Research
Imagine you’re a biologist studying the movement of desert lizards.
istvanhajnal.substack.com
July 19, 2025 at 6:35 PM
istvanhajnal.bsky.social
My latest post on #substack:
"Making sense of #OECD time use data
Using median polish and non-negative matrix factorization to uncover patterns in time use data" istvanhajnal.substack.com/p/making-sen...
#datascience #mrx #rstats #statistics
Making sense of OECD time use data
Using median polish and non-negative matrix factorization to uncover patterns in time use data
istvanhajnal.substack.com
July 5, 2025 at 1:27 PM
istvanhajnal.bsky.social
Went down a calibration rabbit hole 🐇📊 — here's what I found:
istvanhajnal.substack.com/p/calibratio...

#Datascience #statistics #Media #Rstats #Python
Calibration, weighting and post-stratification in audience measurement
The last few months I’ve been working on two very demanding projects in the field of media measurement.
istvanhajnal.substack.com
June 22, 2025 at 7:47 PM
Reposted by Istvan Hajnal
rladiesamsterdam.bsky.social
R-Ladies Amsterdam now has a YouTube channel!

Our first video is @cecibaldoni.bsky.social's excellent talk about how to use @quarto.org and Closeread for scrollytelling science.

This talk was excellent! If you missed it, check it out now! youtu.be/ytKZ357Xtqw?...

#rladies #rstats #scicomm
R-Ladies Amsterdam (English) - Scrollytelling Science with Quarto and Closeread
YouTube video by R-Ladies Amsterdam
youtu.be
June 10, 2025 at 1:56 PM
istvanhajnal.bsky.social
“And she’s buying …a meatball sub to heaven” . The Bread Zeppelin sandwichbar in #Manchester
April 23, 2025 at 12:47 PM
istvanhajnal.bsky.social
Ian Curtis mural, Manchester
April 18, 2025 at 10:57 AM