Philipp Wacker

@phkwacker.bsky.social

190 Followers 567 Following

Senior Lecturer in Statistics, University of Canterbury (NZ). he/him Bayesian stats, Applied Math, filtering & sampling pls send me awesome vegan waffle recipes!

Acute angle
My hand is holding a copy of "The Edge of space-time" by Dr. Chanda Prescod-Weinstein
Ex-prince Andrew reclining in the back of a (possibly police) car, looking panicked and about done with life
four symbols arranged in a 2-by-2 grid (finite versus infinitesimal, and sum versus product). Showing a sum symbol (capital Sigma) for finite sum, an integral symbols for infinitesimal sum, a product symbol (capital Pi) for finite product, and a stylised, integral-font capital P (like an integral symbol with an additional arc for the "belly" of the capital P) for infinitesimal product.
A two-by-two panel showing (top left) a Riemann integral sum approximation \sum_{i=1}^N f(x_i)\Delta x_i, (top right, and connected with an arrow saying "limit") a definite integral \int_a^b f(x) dx. Bottom left: A finite product approximation of the product integral \sum_{i=1}^N (1 + f(x_i)\Delta x_i), connecting to bottom right with an arrow to a product integral \prod_a^b (1+f(x) dx)
A woman in front of a seminar room (implied to be the PhD candidate in a defense), yelling "In conclusion, AAAAAAAA!!!" while charging towards her examiners. Subtitled: The best thesis defense is a good thesis offense
3d-printed microscope in black, gray, and light blue. Shows a power source consisting of 3 AA batteries and badly soldered connections.
u(\cdot) = \cdot^{1-\rho}/(1-\rho), but they used a fancy bold version of \cdot.
(grave) accented beta, boldly generalising the concept of pitch accent from vowels to consonants.
four bits of "woof", on ONE-e-and-e-two-e-AND-e-three-e-AND-e-four-E-and-e
Photo of "Pro-strength Liquid PLUMR clog destroyer gel"
A cartoon panel of an old Victorian (?) home with lots of forest and shrubbery in the background. In the sky above the house the words هاهاها، هاهاها hang in the air, transliterating hearty laughter that can be heard outside
Two long-ish loaves of bread, dark brown color, with diagonal cuts
Just the matrix-dependent quantities: \ln \det \Sigma _{1} - \ln \det \Sigma _{0} - \operatorname {tr} \left(I-\Sigma _{1}^{-1}\Sigma _{0}\right)
A slight rewrite of the KL divergence, pulling apart the logarithmic determinants, and including the constant k as the trace of an identity matrix: {\displaystyle D_{\text{KL}}\left({\mathcal {N}}_{0}\parallel {\mathcal {N}}_{1}\right)={\frac {1}{2}}\left(\ln \det \Sigma _{1} - \ln \det \Sigma _{0} - \operatorname {tr} \left(I-\Sigma _{1}^{-1}\Sigma _{0}\right)+\left(\mu _{1}-\mu _{0}\right)^{\mathsf {T}}\Sigma _{1}^{-1}\left(\mu _{1}-\mu _{0}\right)\right).}
Formula for KL divergence between two Gaussians N_0 and N_1 {\displaystyle D_{\text{KL}}\left({\mathcal {N}}_{0}\parallel {\mathcal {N}}_{1}\right)={\frac {1}{2}}\left(\operatorname {tr} \left(\Sigma _{1}^{-1}\Sigma _{0}\right)-k+\left(\mu _{1}-\mu _{0}\right)^{\mathsf {T}}\Sigma _{1}^{-1}\left(\mu _{1}-\mu _{0}\right)+\ln \left({\frac {\det \Sigma _{1}}{\det \Sigma _{0}}}\right)\right).}
PDF LaTeX output of $Y_i Y_i^\top$ $Y_i {Y_i}^\top$. First version has wrong alignment of i, second one is correct.
PDF LaTeX output of $Y_i Y_i^\top$. The heights of the two indices i are not aligned.
A scary looking storm drain(?) with a placque above it which says "The detention control pit shall be regularly inspected and cleaned"
German FDP politicians giving a press conference with lighting weirdly place below and to the left of them, casting pronounced shadows in their faces
A Venn diagram of five properties: sigma-algebra, algebra, lambda -system, monotone class, and pi-system
Book cover. Title: dont look back, you'll trip over, by Michael Caine
A cosine function on top of a cow, setting up a pun parallel to "elf on a shelf".
More belly-mouth cats
Children's book with two drawn cats. Cats look normal with the exception that their mouths are somehow in the middle of their belly.
It's raining, 2 men and one woman sit in a puddle while some dude tries to convince everyone that pi=3.14, to the confusion of everyone, while notes taken dissolve in the puddle, letters and numbers floating away.
Constant models: Considerable bias, low variance. Polynomial order 5: Low bias, high variance. Quadratic polynomial somewhere in the middle.
Ensemble of order-5 polynomial regression lines, showing a very wide spread of predictions around a ground truth (blue cross)
Ensemble of quadratic regression lines, showing a spread of predictions as a red point cloud around a ground truth (blue cross)
Screenshot of a graph inserted into Microsoft Powerpoint, with the AI-generated Alt Text "A graph of a person in a cave" (which is not what can be seen on the inserted graph at all, instead showing a corner plot with a bivariate distribution). This alt text was not generated by MS Powerpoint
A graphical representation of the following statistics: 240 patients treated with "Treatment A" for kidney stones in total. 200 of them have small stones, with a recovery rate of 85% (with 170 patients recovered). The remaining 40 patients have large stones, with a recovery rate of 65% (26 recovered). In short: 85% of small stones patients recovered, 65% of large stones patients recovered.
A graphical representation of the following statistics: 240 patients treated with "Treatment A" for kidney stones in total. 80 of them have small stones, with a recovery rate of 90% (with 36 patients recovered). The remaining 160 patients have large stones, with a recovery rate of 70% (112 recovered). In short: 90% of small stones patients recovered, 70% of large stones patients recovered.