Name: grubbs test for spotting data outliers
Uploaded: 2024-04-04T10:51:12.000Z
Duration: 1 min 2 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry

CHEM.2

CHEM.2.C

quantifying-and-rejecting-outliers-the-grubbs-test

Quantifying and Rejecting Outliers: The Grubbs Test

La prueba de Grubbs, al igual que la prueba Q de Dixon, es una prueba estadística para identificar los valores atípicos en datos con una distribución normal. En este caso, el número de observaciones debe ser igual o superior a siete.
Para un conjunto de datos dado, esta prueba implica calcular el estadístico G de Grubbs, que es la relación entre la diferencia absoluta entre el valor cuestionable y el valor medio y la desviación estándar de la muestra.
A continuación, el valor G calculado se compara con el valor crítico tabulado de G para un nivel de confianza determinado y el número de observaciones.
Si el valor G calculado supera el valor crítico de G, la observación cuestionable se considera un valor atípico de los datos y se rechaza. 
Alternativamente, si el valor G calculado es menor que el valor crítico de G, los datos conservan la observación cuestionable.

cuantificar y rechazar valores atípicos: la prueba de grubbs

A veces, un conjunto de datos puede tener una observación numérica registrada que se desvía mucho del resto de los datos. Suponiendo que los datos se distribuyen normalmente, se puede utilizar un método estadístico llamado prueba de Grubbs para determinar si la observación es realmente un valor atípico. Para realizar una prueba de Grubbs de dos colas, primero calcule la diferencia absoluta entre el valor atípico y la media. Luego, calcule la relación entre esta diferencia y la desviación estándar de la muestra. Este número se conoce como estadística de Grubbs, 'G'. Cuando el valor G calculado excede el valor crítico G para un nivel de confianza determinado y el número de observaciones, la observación cuestionable se considera un valor atípico y se elimina del conjunto de datos. Por el contrario, si el valor G calculado es menor que el valor G crítico, la observación cuestionable no se considera un valor atípico y, por lo tanto, se retiene en el conjunto de datos.

Cuantificar y rechazar valores atípicos: La prueba de Grubbs

La prueba de Grubbs, al igual que la prueba Q de Dixon, es una prueba estadística para identificar los valores atípicos en datos con una distribución normal. Aquí, el número de ...

Education

Educación

JoVE Core

Analytical Chemistry

Química Analítica

Unit 1

Unidad 1

Chemical Applications of Statistical Analyses

Aplicaciones Químicas de los Análisis Estadísticos

chemical-applications-of-statistical-analyses

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

grubbs test for spotting data outliers

The Grubbs test is a statistical way to spot a possible outlier in a data set. It is used when the data is assumed to follow a normal distribution. A Grubbs test helps decide whether one unusual numerical value should be treated as a true outlier.

To run a two-tailed Grubbs test, first find the absolute difference between the questionable value and the mean. Then divide that difference by the sample standard deviation. The result is the Grubbs statistic, or G.

Next, compare the calculated G value with the G critical value for the chosen confidence level and the number of observations. If the calculated G is larger, the questionable value is considered an outlier and removed from the data set. If the calculated G is smaller, the value is not considered an outlier and is kept in the data set.

Grubbs Test for Spotting Data Outliers

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The Grubbs test is a statistical way to spot a possible outlier in a data set. It is used when the data is assumed to follow a normal distribution. A Grubbs test helps decide whether one unusual numerical value should be treated as a true outlier. To run a two-tailed Grubbs test, first find the absolute difference between the questionable value and the mean. Then divide that difference by the sample standard deviation. The result is the Grubbs statistic, or G. Next, compare the calculated G...

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key terms and concepts

Learn how the Grubbs test checks a normal data set for a possible outlier by comparing the G statistic with the critical value.

Grubbs Test for Spotting Data Outliers | JoVE K12

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Grubbs Test for Spotting Data Outliers

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