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Lära Outlier Detection | Data Quality Essentials
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bookOutlier Detection

Outliers are data points that differ significantly from other observations in your dataset. They matter because they can distort statistical analyses, affect model accuracy, and sometimes indicate underlying problems such as data entry mistakes or unusual but valid phenomena. Common causes of outliers include typographical errors, instrument malfunctions, rare events, and genuine variability in the population being studied.

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# Sample numeric data values <- c(10, 12, 13, 12, 14, 11, 13, 100) # Visual identification using boxplot boxplot(values, main = "Boxplot of Values", ylab = "Value") # Summary statistics mean_value <- mean(values) median_value <- median(values) iqr_value <- IQR(values) summary_stats <- summary(values) print(mean_value) print(median_value) print(iqr_value) print(summary_stats)
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Boxplots make it easy to spot outliers by displaying them as individual points outside the main box and whiskers. The interquartile range (IQR) helps set thresholds for what counts as an outlier: values much lower or higher than the middle 50% of the data are flagged as potential outliers.

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# Calculate IQR-based outlier thresholds q1 <- quantile(values, 0.25) q3 <- quantile(values, 0.75) iqr <- q3 - q1 lower_bound <- q1 - 1.5 * iqr upper_bound <- q3 + 1.5 * iqr # Identify outliers outliers <- values[values < lower_bound | values > upper_bound] print(outliers)
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The 1.5*IQR rule calculates boundaries beyond which data points are considered outliers. By using quantile-based filtering, you can programmatically detect and isolate these extreme values in your data.

1. What visual tool in R is commonly used to spot outliers in a dataset?

2. How does the 1.5*IQR rule help in detecting outliers?

3. Why might you choose to keep or remove outliers in your analysis?

question mark

What visual tool in R is commonly used to spot outliers in a dataset?

Select the correct answer

question mark

How does the 1.5*IQR rule help in detecting outliers?

Select the correct answer

question mark

Why might you choose to keep or remove outliers in your analysis?

Select the correct answer

Var allt tydligt?

Hur kan vi förbättra det?

Tack för dina kommentarer!

Avsnitt 3. Kapitel 3

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bookOutlier Detection

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Outliers are data points that differ significantly from other observations in your dataset. They matter because they can distort statistical analyses, affect model accuracy, and sometimes indicate underlying problems such as data entry mistakes or unusual but valid phenomena. Common causes of outliers include typographical errors, instrument malfunctions, rare events, and genuine variability in the population being studied.

12345678910111213141516
# Sample numeric data values <- c(10, 12, 13, 12, 14, 11, 13, 100) # Visual identification using boxplot boxplot(values, main = "Boxplot of Values", ylab = "Value") # Summary statistics mean_value <- mean(values) median_value <- median(values) iqr_value <- IQR(values) summary_stats <- summary(values) print(mean_value) print(median_value) print(iqr_value) print(summary_stats)
copy

Boxplots make it easy to spot outliers by displaying them as individual points outside the main box and whiskers. The interquartile range (IQR) helps set thresholds for what counts as an outlier: values much lower or higher than the middle 50% of the data are flagged as potential outliers.

1234567891011
# Calculate IQR-based outlier thresholds q1 <- quantile(values, 0.25) q3 <- quantile(values, 0.75) iqr <- q3 - q1 lower_bound <- q1 - 1.5 * iqr upper_bound <- q3 + 1.5 * iqr # Identify outliers outliers <- values[values < lower_bound | values > upper_bound] print(outliers)
copy

The 1.5*IQR rule calculates boundaries beyond which data points are considered outliers. By using quantile-based filtering, you can programmatically detect and isolate these extreme values in your data.

1. What visual tool in R is commonly used to spot outliers in a dataset?

2. How does the 1.5*IQR rule help in detecting outliers?

3. Why might you choose to keep or remove outliers in your analysis?

question mark

What visual tool in R is commonly used to spot outliers in a dataset?

Select the correct answer

question mark

How does the 1.5*IQR rule help in detecting outliers?

Select the correct answer

question mark

Why might you choose to keep or remove outliers in your analysis?

Select the correct answer

Var allt tydligt?

Hur kan vi förbättra det?

Tack för dina kommentarer!

Avsnitt 3. Kapitel 3
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