Statistik

P-værdi

Den officelle definition af p-værdien fra American Statistical Association (ASA):

The ASA panel defined the P value as “the probability under a specified statistical model that a statistical summary of the data (for example, the sample mean difference between two compared groups) would be equal to or more extreme than its observed value.”1

ASA forstætter med at piontere den problematiske omgang med p-værdien:

Part of the problem lies in how people interpret P values. According to the ASA statement, “A conclusion does not immediately become ‘true’ on one side of the divide and ‘false’ on the other.” Valuable information may be lost because researchers may not pursue “insignificant” results. Conversely, small effects with “significant” P values may be biologically or clinically unimportant. At best, such practices may slow scientific progress and waste resources. At worst, they may cause grievous harm when adverse effects go unreported. The Supreme Court case involved the drug Zicam, which caused permanent hearing loss in some users. Another drug, rofecoxib (Vioxx), was taken off the market because of adverse cardiovascular effects. The drug companies involved did not report those adverse effects because of lack of statistical significance in the original drug tests (Rev. Soc. Econ. 2016;74:83–97; doi:10.1080⁄00346764.2016.1150730).2

Godt eksempel fra /u/Ufarious på Reddit:

A P-value actually tells us the likelihood that you observe this outcome in your data given that your counter-assumption is true (i.e. a true null hypothesis). Remember that in statistical testing, you have an assumption you are studying (for example, let’s assume that smoking cigarettes makes you live longer) and the opposite of that assumption (smoking does not make you live longer). The assumption is called your hypothesis and the counter-assumption is called your null hypothesis. In a statistical test, we make a conclusion by rejecting the null hypothesis, or being able to confidently say that the opposite of our study’s assumption is NOT true. I know it’s confusing that statisticians take a double-negative approach, but it’s the best we can do given the limits of what we can do with our math.

Now, we know that smoking cigarettes doesn’t help you live longer, so the counter-assumption is actually true. But there is a chance that our study will incorrectly show a connection between smoking and a longer life. If we have a P-Value of 0.05 for our data, this means that given that smoking doesn’t makes us live longer, we will still see a connection between smoking and a long life 5% of the time.

Most importantly, notice that the statement above tells us NOTHING about the likelihood that our assumption (or counter-assumption) is true (or false). A P-value cannot tell us how confident we are that we got the “right” results or how likely it is that our results were due to chance. Given that there is no connection, random chance will will tell us there is a connection some of the time. The percent of times we can expect to get this wrong is the P-Value.3

En dansk (uofficel) definition:

P-værdien er sandsynligheden for at gøre en observation som afviger mindst lige så meget fra nulhypotesen som det konkrete resultat….

… Kan betegnes som den grænse (typisk på 5 %) for hvornår nulhypotesen forkastes. Det vil sige hvis p-værdien er mindre end det valgte niveau, altså fx 5, forkastes H0, hvilket som regel åbner op for en mere interessant forklaring. Hvis p-værdien er højere end det valgte niveau, fx 20 %, forkastes nulhypotesen ikke, hvilket vil sige at man ikke kan afvise nulhypotesen da man ikke har beviser nok til at påvise det modsatte. Jo lavere signifikansniveau, jo større skal Q være for at man kan forkaste H0. Dvs. hvis man vælger et signifikansniveau på 2 %, skal Q være væsentlig større for at man kan forkaste nulhypotesen.4

Hypoteseprøvning

“Statistical hypothesis testing” på engelsk, “Statistischer Test” på tysk og “Test statistique” på fransk.

Hypoteseprøvning (eller hypotesetest) er en statistisk metode, der benyttes til at undersøge om en hypotese understøttes eller ej af en stikprøve.5

Nye ord

  • schnackseln, geschnackselt (sydtysk, østrigsk) = have it off, bonk, have sex
  • pudern, gepudert (østrigsk) = have sex eller pudre
  • Knalltüte = twerp, forrykte person

Sublimierung

Sublimierung. Der dritte Ausgang bei abnormer konstitutioneller Anlage wird durch den Prozeß der »Sublimierung« ermöglicht, bei welchem den überstarken Erregungen aus einzelnen Sexualitätsquellen Abfluß und Verwendung auf andere Gebiete eröffnet wird, so daß eine nicht unerhebliche Steigerung der psychischen Leistungsfähigkeit aus der an sich gefährlichen Veranlagung resultiert.6

Kommaregler

Basisregler for kommatering på dansk:

  1. Komma ved ledsætninger. Ledsætninger kendes ofte på at de starter med: at, som, der, når, da, fordi, hv-ord

  2. Komma mellem helsætninger forbundet med f.eks.: og, men, eller, for eller så

  3. Komma ved opremsninger

  4. Komma ved selvstændige sætningsdele (samt parentetiske ledsætninger)

Læs mere om kommareglerne.

Fødevareinstituttets offentlige fødevaredatabase

URL: https://frida.fooddata.dk/

Resonanz

Wenn Beschleunigung das Problem ist, dann ist Resonanz vielleicht die Lösung. 6

Wikipedia: https://en.wikipedia.org/wiki/Resonance_(sociology)

Node introduction and useful examples

https://nodejs.dev/learn/introduction-to-nodejs

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5017929/ [return]
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5017929/ [return]
  3. https://en.reddit.com/r/explainlikeimfive/comments/apa3gc/eli5_what_is_p_value_and_why_is_005_so_important/eg70vsm/ [return]
  4. https://sites.google.com/site/mfg2amabstat/home/p-vaerdi-og-signifikansniveau [return]
  5. https://da.wikipedia.org/wiki/Hypotesepr%C3%B8vning [return]
  6. https://www.ulrich-schachtschneider.de/resources/Rosa-Resonanz.pdf [return]