Have a deep view into what people are curious about.

🔗 Mathematics 🔗 Statistics

The secretary problem is a problem that demonstrates a scenario involving optimal stopping theory. The problem has been studied extensively in the fields of applied probability, statistics, and decision theory. It is also known as the marriage problem, the sultan's dowry problem, the fussy suitor problem, the googol game, and the best choice problem.

The basic form of the problem is the following: imagine an administrator who wants to hire the best secretary out of ${\displaystyle n}$ rankable applicants for a position. The applicants are interviewed one by one in random order. A decision about each particular applicant is to be made immediately after the interview. Once rejected, an applicant cannot be recalled. During the interview, the administrator gains information sufficient to rank the applicant among all applicants interviewed so far, but is unaware of the quality of yet unseen applicants. The question is about the optimal strategy (stopping rule) to maximize the probability of selecting the best applicant. If the decision can be deferred to the end, this can be solved by the simple maximum selection algorithm of tracking the running maximum (and who achieved it), and selecting the overall maximum at the end. The difficulty is that the decision must be made immediately.

The shortest rigorous proof known so far is provided by the odds algorithm (Bruss 2000). It implies that the optimal win probability is always at least ${\displaystyle 1/e}$ (where e is the base of the natural logarithm), and that the latter holds even in a much greater generality (2003). The optimal stopping rule prescribes always rejecting the first ${\displaystyle \sim n/e}$ applicants that are interviewed and then stopping at the first applicant who is better than every applicant interviewed so far (or continuing to the last applicant if this never occurs). Sometimes this strategy is called the ${\displaystyle 1/e}$ stopping rule, because the probability of stopping at the best applicant with this strategy is about ${\displaystyle 1/e}$ already for moderate values of ${\displaystyle n}$. One reason why the secretary problem has received so much attention is that the optimal policy for the problem (the stopping rule) is simple and selects the single best candidate about 37% of the time, irrespective of whether there are 100 or 100 million applicants.

Add A Fact is a temporary experimental tool created by the Wikimedia Foundation's Future Audience team to learn how and if we can support making it possible to contribute productively to Wikipedia from outside of Wikipedia, and if guidance to the contributor from a large language model (LLM) could be useful in this process. The idea was developed and workshopped with Wikipedians at WikiConference North America 2023, demoed and tested with Wikipedia community members as part of our team’s regular monthly community calls.

Add A Fact is available for the Google Chrome and Mozilla Firefox browsers and can be used by any logged in, autoconfirmed English Wikipedia user. We welcome your feedback on the talk page of this page, or via the Feedback tool in the browser extension.

🔗 Medicine 🔗 Psychology

Posttraumatic Embitterment Disorder (PTED) is defined as a pathological reaction to a negative life event, which those affected experienced as a grave insult, humiliation, betrayal, or injustice. Prevalent emotions of PTED are embitterment, anger, fury, and hatred, especially against the triggering stressor, often accompanied by fantasies of revenge. The disorder commences immediately and without time delay at the moment of the triggering event. If left untreated, the prognosis of PTED presents as rather unfavorable, since patients find themselves trapped in a vicious circle of strong negative emotions constantly intensifying one another and eventually leading into a self-destructive downward spiral. People affected by PTED are more likely to put fantasies of revenge into action, making them a serious threat to the stressor.

The concept of PTED as a distinct clinical disorder has been first described by the German psychiatrist and psychologist Michael Linden in 2003, who remains its most involved researcher. Even though it has been backed up by empirical research in the past years, it remains disputed as to whether embitterment should be included among psychological disorders. Therefore, PTED currently does not hold its own category in the ICD-10 but is categorized under F43.8 “Other reactions to severe stress”. It cannot be categorized as an adjustment disorder under F43.2, since “ordinary” adjustment disorders normally subside within six months, while PTED is much more likely to become chronical and last for much longer. A condition similar to PTED has already been described by Emil Kraepelin as early as 1915 by the name querulous paranoia as a form of traumatic neuroses, explicitly demarcating it from personality disorders.

🔗 Architecture 🔗 Firearms 🔗 Metalworking

A shot tower is a tower designed for the production of small diameter shot balls by freefall of molten lead, which is then caught in a water basin. The shot is primarily used for projectiles in shotguns, and also for ballast, radiation shielding and other applications where small lead balls are useful.

🔗 Mathematics 🔗 Statistics

Simpson's paradox, which goes by several names, is a phenomenon in probability and statistics, in which a trend appears in several different groups of data but disappears or reverses when these groups are combined. This result is often encountered in social-science and medical-science statistics and is particularly problematic when frequency data is unduly given causal interpretations. The paradox can be resolved when causal relations are appropriately addressed in the statistical modeling.

Simpson's paradox has been used as an exemplar to illustrate to the non-specialist or public audience the kind of misleading results mis-applied statistics can generate. Martin Gardner wrote a popular account of Simpson's paradox in his March 1976 Mathematical Games column in Scientific American.

Edward H. Simpson first described this phenomenon in a technical paper in 1951, but the statisticians Karl Pearson et al., in 1899, and Udny Yule, in 1903, had mentioned similar effects earlier. The name Simpson's paradox was introduced by Colin R. Blyth in 1972.

It is also referred to as or Simpson's reversal, Yule–Simpson effect, amalgamation paradox, or reversal paradox.

🔗 Time

Segal's law is an adage that states:

A man with a watch knows what time it is. A man with two watches is never sure.

At surface level, the adage emphasizes the consistency that arises when information comes from a single source and points out the potential pitfalls of having too much conflicting information. However, the underlying message is to question the apparent certainty of anyone who only has one source of information. The man with one watch has no way to identify error or uncertainty.

🔗 United States/U.S. Government 🔗 United States 🔗 Medicine 🔗 Economics 🔗 Politics 🔗 Geography

Universal healthcare (also called universal health coverage, universal coverage, or universal care) is a health care system in which all residents of a particular country or region are assured access to health care. It is generally organized around providing either all residents or only those who cannot afford on their own, with either health services or the means to acquire them, with the end goal of improving health outcomes.

Universal healthcare does not imply coverage for all cases and for all people – only that all people have access to healthcare when and where needed without financial hardship. Some universal healthcare systems are government-funded, while others are based on a requirement that all citizens purchase private health insurance. Universal healthcare can be determined by three critical dimensions: who is covered, what services are covered, and how much of the cost is covered. It is described by the World Health Organization as a situation where citizens can access health services without incurring financial hardship. The Director General of WHO describes universal health coverage as the “single most powerful concept that public health has to offer” since it unifies “services and delivers them in a comprehensive and integrated way”. One of the goals with universal healthcare is to create a system of protection which provides equality of opportunity for people to enjoy the highest possible level of health.

As part of Sustainable Development Goals, United Nations member states have agreed to work toward worldwide universal health coverage by 2030.

Digital Radio Frequency Memory (DRFM) is an electronic method for digitally capturing and retransmitting RF signals. DRFM systems are typically used in radar jamming, although applications in cellular communications are becoming more common.

🔗 Germany 🔗 Brands 🔗 Automobiles 🔗 Germany/GDR

Trabant (German: [tʁaˈbant] ) is a series of small cars produced from 1957 until 1991 by former East German car manufacturer VEB Sachsenring Automobilwerke Zwickau. Four models were made: the Trabant 500, Trabant 600, Trabant 601, and the Trabant 1.1. The first model, the 500, was a relatively modern car when it was introduced.

It featured a duroplast body on a steel chassis, front-wheel drive, a transverse two-stroke engine, and independent suspension. Because this 1950s design remained largely unchanged until the introduction of the last model, the Trabant 1.1 in 1990, the Trabant became symbolic of the former East Germany's stagnant economy and the collapse of the Eastern Bloc in general. Called "a spark plug with a roof", 3,096,999 Trabants were produced. Older models have been sought by collectors in the United States due to their low cost and fewer restrictions on the importation of antique cars. The Trabant also gained a following among car tuning and rallying enthusiasts.

🔗 China

"I would rather cry in a BMW" is a quotation that became an online sensation in the People's Republic of China in 2010. The old, long-familiar phrase was made famous by Ma Nuo, a 20-year-old female contestant on the television show Fei Cheng Wu Rao (also known in English as If You Are the One). The line was in response to a question by an unemployed suitor who asked if Ma would "ride a bicycle with him" on a date. The series of events have been summed up in the media with the quip "I would rather cry in a BMW than smile on a bicycle."