Vitale tegn er ikke parametrer, men variabler!

 

Begrepene variabel hhv. parameter

Variabel:
"Any quantity that varies. Any attribute, phenomenon, or event that can have different values."

En variabel er et definert (navngitt) objekt som kan innta ulike verdier. Kliniske funn eller målinger hos pasienten er kliniske variabler.

Parameter:

"In mathematics, a constant in a formula or model, in statistics and epidemiology, a measureable characteristic of a population."

 

En parameter er oftest en konstant verdi for en bestemt anvendelse og som kan karakterisere denne anvendelsen.

I klinisk sammenheng representerer en parameter en målestørrelse hvis variasjoner fører til variasjoner i måleresultatet (for variabelen man måler). Eksempler på parametre er oksygenflow, kroppsstilling, romtemperatur etc.

 

Måleresultatene for variablene blodtrykk, puls, oksygenmetning, ventilasjonsfrekvens etc. kan være avhengig av ulike parametrer som kroppsstilling, aktivitet,oksygenflow, ytre temperatur etc., som under enkeltmålinger vil være konstant, men vil kunne variere fra måling til måling.

 

Variabler er det man måler, mens parameter er populært sagt ”det som er utenfor”.

For å unngå feil bruk av fremmedord er det enkleste alltid å bruke "Vitale tegn".

Begrepene brukes feil og bøyes feil

Generelt brukes og bøyes disse ordene ofte feil: Det heter én variabel – flere variabler (selv om «alle» skriver flere variable).
Dessuten benyttes svært ofte parameter i stedet for variabel.
Termene variabel og parameter brukes ofte som synonymer, men det er ikke er korrekt.

 

Begrunnelse/referanse

Kunnskapssenteret (i ordliste 2010):

Variabel
En faktor som varierer. Variabler inkluder pasientegenskaper, f.eks. alder, kjønn og røyking, målinger, f.eks. blodtrykk og depresjonsskåre, behandlings- eller tilstandsvariabler,
f.eks. i en barnefødselsstudie, hvor lenge den fødende har rier, samt utfallsvariabler.

Parameter
En størrelse som definerer en teoretisk modell. I motsetning til variabler er ikke parametrer relatert til faktiske målinger eller egenskaper ved pasienter.

Kjønn og bøyninger (fra Bokmålsordboka)

m.

en variabel

variabelen

variabler

variablene

m.

en parameter

parameteren

 parametrer

 parametrene

 

 

Variabel versus parameter - nærmere omtale

 Ofte uttrykkes forskjellen slik:

“There is a clear difference between variables and parameters. A variable represents a model state, and may change during simulation.

A parameter is commonly used to describe objects statically. A parameter is normally a constant in a single simulation, and is changed only when you need to adjust your model behavior.”

https://anylogic.help/anylogic/data/parameters-and-variables.html#:~:text=There%20is%20a%20clear%20difference,to%20adjust%20your%20model%20behavior.

 

eller slik:

 

“Variable and parameter are two terms widely used in mathematics and physics. These two are commonly misunderstood as the same entity.

A variable is an entity that changes with respect to another entity.

A parameter is an entity which is used to connect variables.

The concepts of variable and parameter are very important in fields such as mathematics, physics, statistics, analysis and any other field that has usages of mathematics. In this article, we are going to discuss what variable and parameter are, their definitions, the similarities between variable and parameter, the applications of variable and parameter, some common usages of variable and parameter, and finally the difference between variable and parameter.”
https://www.differencebetween.com/difference-between-variable-and-vs-parameter/

Som nevnt ovenfor har termen parameter en egen betydning i statistikk:

En parameter er et tall som beskriver en egenskap til populasjonen. Verdien til en parameter er i praksis ikke kjent. Dette er fordi vi stort sett i praksis ikke kan undersøke hele populasjonen. En observator (eller statistikk) er et tall som beskriver en egenskap til et utvalg.

En observator (eller statistikk) er et tall som beskriver en egenskap til et utvalg. Verdien til en observator kan regnes ut direkte fra utvalgsdataene, men den kan variere fra utvalg til utvalg. Vi bruker ofte en observator til å estimere en ukjent parameter.

 Fra forelesning om Statistisk inferens (Kunsten å trekke konklusjoner om en stor populasjon fra et mindre utvalg) UiO

https://www.uio.no/studier/emner/matnat/math/STK1000/h21/forelesningspresentasjoner/kapittel5_mlh21.pdf

Vitale tegn er ikke parametrer, men variabler!

 

Artikkelen i BMJ (1999) er klargjørende og lesverdig:

 Artikkelen er lettlest, kort og presis og kan forebygge begrepsforvirring.

https://www.bmj.com/content/318/7199/1667

 

“Parameter is a technical term which has only recently found its way into general use, unfortunately without keeping its correct meaning. It is common in medical journals to find variables incorrectly called parameters (but not in the BMJ we hope). Another common misuse of parameter is as a limit or boundary, as in “within certain parameters.” This misuse seems to have arisen from confusion between parameter and perimeter.

Misuse of medical terms is rightly deprecated. Like other language errors it leads to confusion and the loss of valuable distinction. Misuse of non-medical terms should be viewed likewise.”

 

 

Dagens tekst: Vitale tegn, vitale tegn, vitale tegn....


 

Statistics notes Variables and parameters

BMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7199.1667 (Published 19 June 1999)Cite this as: BMJ 1999;318:1667
  1. Douglas G Altman, professor of statistics in medicinea,  
  2. J Martin Bland, professor of medical statisticsb
    Author affiliations
  1. Correspondence to: Professor Altman

Like all specialist areas, statistics has developed its own language. As we have noted before,1 much confusion may arise when a word in common use is also given a technical meaning. Statistics abounds in such terms, including normal, random, variance, significant, etc. Two commonly confused terms are variable and parameter; here we explain and contrast them.

Information recorded about a sample of individuals (often patients) comprises measurements such as blood pressure, age, or weight and attributes such as blood group, stage of disease, and diabetes. Values of these will vary among the subjects; in this context blood pressure, weight, blood group and so on are variables. Variables are quantities which vary from individual to individual.

By contrast, parameters do not relate to actual measurements or attributes but to quantities defining a theoretical model. The figure shows the distribution of measurements of serum albumin in 481 white men aged over 20 with mean 46.14 and standard deviation 3.08 g/l. For the empirical datathe mean and SD are called sample estimates. They are properties of the collection of individuals.Also shown is the normal1 distribution which fits the data most closely. It too has mean 46.14 and SD 3.08 g/l. For the theoretical distribution the mean and SD are called parameters. There is not one normal distribution but many, called a family of distributions. Each member of the family is defined by its mean and SD, the parameters1 which specify the particular theoretical normal distribution with which we are dealing. In this case, they give the best estimate of the population distribution of serum albumin if we can assume that in the population serum albumin has a normal distribution.

Measurements of serum albumin in 481 white men aged over 20 (data from Dr W G Miller)

Most statistical methods, such as t tests, are called parametric because they estimate parameters of some underlying theoretical distribution. Non-parametric methods, such as the Mann-Whitney U test and the log rank test for survival data, do not assume any particular family for the distribution of the data and so do not estimate any parameters for such a distribution.

Another use of the word parameter relates to its original mathematical meaning as the value(s) defining one of a family of curves. If we fit a regression model, such as that describing the relation between lung function and height, the slope and intercept of this line (more generally known as regression coefficients) are the parameters defining the model. They have no meaning for individuals, although they can be used to predict an individual's lung function from their height.

In some contexts parameters are values that can be altered to see what happens to the performance of some system. For example, the performance of a screening programme (such as positive predictive value or cost effectiveness) will depend on aspects such as the sensitivity and specificity ofthe screening test. If we look to see how the performance would change if, say, sensitivity and specificity were improved, then we are treating these as parameters rather than using the values observed in a real set of data.

Parameter is a technical term which has only recently found its way into general use, unfortunately without keeping its correct meaning. It is common in medical journals to find variables incorrectly called parameters (but not in the BMJ we hope2). Another common misuse of parameter is as a limit or boundary, as in “within certain parameters.” This misuse seems to have arisen from confusion between parameter and perimeter.

Misuse of medical terms is rightly deprecated. Like other language errors it leads to confusion and the loss of valuable distinction. Misuse of non-medical terms should be viewed likewise.

References

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  2. 2.
View Abstract