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

O teste de Grubbs, como o teste Q de Dixon, é um teste estatístico para identificar os outliers nos dados com uma distribuição normal. Aqui, o número de observações deve ser igual ou superior a sete.
Para um determinado conjunto de dados, este teste envolve o cálculo da estatística de Grubbs G, que é a razão entre a diferença absoluta entre o valor questionável e o valor médio e o desvio padrão da amostra.
O valor G calculado é então comparado com o valor crítico tabulado de G para um determinado nível de confiança e o número de observações.
Se o valor G calculado exceder o valor crítico de G, a observação questionável é considerada um valor discrepante dos dados e rejeitada. 
Alternativamente, se o valor G calculado for menor que o valor crítico de G, os dados retêm a observação questionável.

quantificando e rejeitando valores atípicos: o teste de grubbs

Às vezes, um conjunto de dados pode ter uma observação numérica registrada que se desvia bastante do restante dos dados. Supondo que os dados sejam distribuídos normalmente, um método estatístico chamado teste de Grubbs pode ser usado para determinar se a observação é realmente uma exceção. Para realizar um teste de Grubbs bicaudal, primeiro calcule a diferença absoluta entre o valor atípico e a média. Em seguida, calcule a razão entre essa diferença e o desvio padrão da amostra. Este número é conhecido como estatística de Grubbs, 'G.' Quando o valor G calculado excede o valor crítico G para um determinado nível de confiança e o número de observações, a observação questionável é considerada um valor discrepante e removida do conjunto de dados. Pelo contrário, se o valor G calculado for menor que o valor crítico de G, a observação questionável não é considerada um valor atípico e, portanto,é retida no conjunto de dados.

Quantificando e Rejeitando Valores Atípicos: O Teste de Grubbs

O teste de Grubbs, como o teste Q de Dixon, é um teste estatístico para identificar os outliers nos dados com uma distribuição normal. Aqui, o número de ...

Education

JoVE Core

Analytical Chemistry

Química Analítica

Unit 1

Unidade 1

Chemical Applications of Statistical Analyses

Aplicações Químicas de Análises Estatísticas

chemical-applications-of-statistical-analyses

KEY TERMS AND CONCEPTS

TERMOS E CONCEITOS-CHAVE

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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quantifying and rejecting outliers: the grubbs test

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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