map   85234
Oxidizing Source Maps with Rust and WebAssembly – Mozilla Hacks – the Web developer blog
A detailed look at how we replaced the most performance-sensitive portions of the source-map JavaScript Library’s source map parser with Rust code that is compiled to WebAssembly. The results: The ...
source  map  rust  javascript  4*
1 hour ago by ianweatherhogg
The tools that convinced a federal court to strike down North Carolina’s gerrymander
ASYMMETRY * CONSISTENT ADVANTAGE * EFFICIENCY GAP * DURABILITY * GEOGRAPHY

“Asymmetry” refers to situations in which identical performances by the two parties lead to very different results. Say, when one party gets 52 percent of the statewide vote in legislative elections, it wins a significant majority of the seats, but when the other party wins 52 percent of the vote, it wins only a minority of seats. However, the Supreme Court has explicitly, and correctly, concluded that a one-off outcome like the 52 percent example cannot be used to prove a gerrymander, because such an outcome could occur by chance.

Student’s test is the basis for a very simple measure of asymmetry, the “lopsided-wins test,” which checks if Democratic representatives won, on average, with much larger margins than Republican representatives. If the difference is large enough, and there is enough data — these statistical tests are always stronger the more data points there are — then their average is highly unlikely to have arisen from neutral principles.

In North Carolina in 2016, the three Democratic winners took an average of 68.5 percent of the vote, while the 10 Republican winners took an average of only 60.3 percent of the vote. According to the lopsided wins test, such a pattern would have only occurred by chance in one of 300 cases. Importantly, it doesn’t matter that Democrats won three seats; if they’d won four or five seats with similar averages, the lopsided wins still suggest that Democrats were denied an equal opportunity to elect representatives of their choice — but without suggesting a quota of seats.

An even older way to measure unequal opportunity is a test for “consistent advantage,” originally developed by Gosset’s mathematical mentor Karl Pearson in 1895. To carry out this test, compare the average statewide vote captured by each party with that of the median district — the district that falls in the middle when they are ranked by one party’s vote share.

When both parties are treated similarly, this difference is close to zero. If the “average-median difference” is large — with the median district tilted strongly toward one party — it means that one party gained a consistent advantage at the district level. Call it the Lake Wobegon test: The redistricting party has ensured that a majority of its districts perform above the statewide average.

The efficiency gap measures the portion of votes each party has “wasted.” For example, in a district where party A defeats party B by a 60-40 margin, party A wasted 10 percent of the votes cast, since they were in excess of the bare 50 percent plus one vote needed to win. All of party B’s 40 percent were wasted.

This definition seems abstruse, but there is a much simpler way to think about it. The efficiency gap is zero when one party wins 50 percent of the statewide vote and 50 percent of the seats — but it is also zero for other election outcomes. For example, it is zero when 75 percent of the statewide vote elects 100 percent of the seats. This graph shows all the outcomes that are associated with an efficiency gap of zero.

Judges are also interested in durability: whether a gerrymander is likely to last under a variety of political conditions.

geography, not gerrymandering.

To sort out the question, the court relied on expert witnesses who drew thousands of alternative maps and concluded that North Carolina’s geography carries no such inherent bias. There were many ways to draw maps following all the redistricting rules that did not lead to unfairness, they showed.
gerrymandering  map  politics  GOP  votingRights  voterSuppression
16 hours ago by campylobacter
USGS historical topo maps
Browse historical USGS maps easily via map/timeline interface
map  maps  USGS  topo
19 hours ago by jasonferrier
[unknown title]
RT : The majority of humanity lives within a relatively small bandwidth of latitude. This is one of my all time fav…