## Anyone else who makes little money get sad when you visit this sub?

I love cars, especially fun/fast ones. Just like most men. But man does it suck to make a small salary and visit this sub, seeing the types of cars everyone else gets to enjoy lol. Here’s to driving a beater Japanese reliable car for the next 10 years.

submitted by Nevin Manimala Nevin Manimala /u/aboutcheese

## Counting directed animals (polyominoes)

I’ve been trying to understand how this algorithm to count directed animals works. I understand the bit manipulations but I’m still mystified by the algorithm. I translated it from C to Python. The first comment is from the original.

In python 3:

``# count number of ways to put `left' counters beyond a # diagonal containing the counter pattern represented by # bitmask `mask' # a<<b is a muliplied by 2^b # ~a is the two's complement of a # | and & are bitwise 'or' and 'and' def tryit(mask,length,left): newmask = ~(mask | (mask<<1)) s=0 m=1<<length while m: if not (m & newmask): ml=m l=left while ml: ml&=ml-1 l-=1 x=(not l) if l<=0 else tryit(m,length+1,l) s += int(x) m-=1 return s; for i in range(2,13): print(i, tryit(1,2,i-1)) # 2 2 # 3 5 # 4 13 # 5 35 # 6 96 # 7 267 # 8 750 # 9 2123 # 10 6046 # 11 17303 # 12 49721 ``

In C:

``#include<stdio.h> typedef unsigned long ul; int try(mask,len,left) /* count number of ways to put `left' counters beyond a diagonal */ /* containing the counter pattern represented by bitmask `mask' */ ul mask; int len,left; { ul m,ml; int l,s; mask = ~(mask | (mask<<1)); for (s=0,m=1<<len; --m;) if (!(m & mask)) { for (ml=m,l=left; ml; ml&=(ml-1)) l--; s += (l<=0 ? !l : try(m,len+1,l)); } return s; } void main() { int i; for (i=2; i<16; i++) printf("%2d:%8dn", i, try(1,2,i-1)); } ``

submitted by Nevin Manimala Nevin Manimala /u/CylonSaydrah

## “Magnitude-Based Inference” banned From a major sports science journal

I know next to nothing about MBI, but it sounds like it was invented to sidestep issues with low powered studies, rather than improve our ability to detect real effects. Are there flawed methods like this floating around in other fields?

Sports performance is a difficult thing to study. There are only so many trained athletes available for experiments, and most of the measurements required to investigate human performance are time-consuming to collect. As a result, most sports science studies are small, and that means it can be difficult to tease out the signal from the noise. In 2006, Will Hopkins and Alan Batterham published a commentary proposing a method for making meaningful inferences in such situations.

Their method, “magnitude-based inference,” or MBI, was controversial from the start. It was rebutted in 2008 by two statisticians who concluded that it was generally unreliable and represented an improper use of existing statistical methods. In 2009, the flagship journal of the American College of Sports Medicine, Medicine and Science in Sports and Exercise, published a set of statistical guidelines for the journal that included a description of MBI, but the journal published it as an invited commentary after peer reviewers would not agree to accept it. Since then, MSSE has published two critiques of MBI that concluded the method was too flawed to be used (the most recent of which arose from reporting by FiveThirtyEight). Now FiveThirtyEight has learned that MSSE has decided to stop accepting papers that use MBI.

https://fivethirtyeight.com/features/a-flawed-statistical-method-was-just-banned-from-a-major-sports-science-journal/

submitted by Nevin Manimala Nevin Manimala /u/Chicagodivemaster

## Is it possible to calculate where a z coordinate would theoretically be on a 2D plane?

I guess this is kind of what I’m talking about. Where the x, y, and z axis lines are all the same length, but the z isn’t actually there. I started thinking about this as I was drawing 3D coordinate planes on 2D paper. I know how the z axis should be drawn, but I don’t know how I know it. I’m sorry if this doesn’t make sense, I’m finding it hard to explain.

submitted by Nevin Manimala Nevin Manimala /u/username43545