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Lære Visual Inspection of Data | Exploratory Data Analysis (EDA) in R
Visualization and Reporting with R

bookVisual Inspection of Data

When you begin exploratory data analysis (EDA), your first step is often to visually inspect your data. Plotting data distributions allows you to quickly understand the shape, spread, and possible issues within your dataset. Visual inspection is crucial because it helps you spot patterns, detect anomalies, and choose the right statistical methods for deeper analysis. Without visualizing your data, important trends or outliers might go unnoticed, leading to misleading conclusions or missed opportunities for insight.

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# Creating a histogram to visualize the distribution of a numeric variable library(ggplot2) # Example dataset: mtcars, focusing on the 'mpg' (miles per gallon) column ggplot(mtcars, aes(x = mpg)) + geom_histogram(binwidth = 5, fill = "skyblue", color = "black") + labs(title = "Histogram of Miles Per Gallon", x = "Miles Per Gallon (mpg)", y = "Frequency")
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A histogram is a common plot for visualizing the distribution of numeric data. It divides the data into intervals called bins, then shows how many data points fall into each bin. The height of each bar represents the frequency of observations within that bin. The overall shape of the histogram can reveal whether your data is symmetric, skewed, has multiple peaks, or contains gaps. For instance, a bell-shaped histogram might indicate a normal distribution, while a long tail on one side suggests skewness.

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# Creating a boxplot to visualize spread and spot outliers library(ggplot2) ggplot(mtcars, aes(y = mpg)) + geom_boxplot(fill = "lightgreen", outlier.color = "red") + labs(title = "Boxplot of Miles Per Gallon", y = "Miles Per Gallon (mpg)")
copy

Boxplots are powerful tools for understanding the spread of your data and identifying potential outliers. In a boxplot, the central box shows the interquartile range (IQR), which contains the middle 50% of your data. The line inside the box marks the median. Whiskers extend to the smallest and largest values within 1.5 times the IQR from the box. Points plotted beyond the whiskers are considered potential outliers. By examining the box, whiskers, and any outlier points, you can quickly assess the symmetry, variability, and unusual observations in your data.

Note
Note

Histograms are best for visualizing the overall shape and frequency of data, while boxplots summarize spread and highlight outliers. Try using both together for a more complete picture of your data.

1. What does a histogram show about your data?

2. How can a boxplot help you identify outliers?

question mark

What does a histogram show about your data?

Select the correct answer

question mark

How can a boxplot help you identify outliers?

Select the correct answer

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Hvordan kan vi forbedre det?

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Seksjon 2. Kapittel 3

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bookVisual Inspection of Data

Sveip for å vise menyen

When you begin exploratory data analysis (EDA), your first step is often to visually inspect your data. Plotting data distributions allows you to quickly understand the shape, spread, and possible issues within your dataset. Visual inspection is crucial because it helps you spot patterns, detect anomalies, and choose the right statistical methods for deeper analysis. Without visualizing your data, important trends or outliers might go unnoticed, leading to misleading conclusions or missed opportunities for insight.

1234567
# Creating a histogram to visualize the distribution of a numeric variable library(ggplot2) # Example dataset: mtcars, focusing on the 'mpg' (miles per gallon) column ggplot(mtcars, aes(x = mpg)) + geom_histogram(binwidth = 5, fill = "skyblue", color = "black") + labs(title = "Histogram of Miles Per Gallon", x = "Miles Per Gallon (mpg)", y = "Frequency")
copy

A histogram is a common plot for visualizing the distribution of numeric data. It divides the data into intervals called bins, then shows how many data points fall into each bin. The height of each bar represents the frequency of observations within that bin. The overall shape of the histogram can reveal whether your data is symmetric, skewed, has multiple peaks, or contains gaps. For instance, a bell-shaped histogram might indicate a normal distribution, while a long tail on one side suggests skewness.

123456
# Creating a boxplot to visualize spread and spot outliers library(ggplot2) ggplot(mtcars, aes(y = mpg)) + geom_boxplot(fill = "lightgreen", outlier.color = "red") + labs(title = "Boxplot of Miles Per Gallon", y = "Miles Per Gallon (mpg)")
copy

Boxplots are powerful tools for understanding the spread of your data and identifying potential outliers. In a boxplot, the central box shows the interquartile range (IQR), which contains the middle 50% of your data. The line inside the box marks the median. Whiskers extend to the smallest and largest values within 1.5 times the IQR from the box. Points plotted beyond the whiskers are considered potential outliers. By examining the box, whiskers, and any outlier points, you can quickly assess the symmetry, variability, and unusual observations in your data.

Note
Note

Histograms are best for visualizing the overall shape and frequency of data, while boxplots summarize spread and highlight outliers. Try using both together for a more complete picture of your data.

1. What does a histogram show about your data?

2. How can a boxplot help you identify outliers?

question mark

What does a histogram show about your data?

Select the correct answer

question mark

How can a boxplot help you identify outliers?

Select the correct answer

Alt var klart?

Hvordan kan vi forbedre det?

Takk for tilbakemeldingene dine!

Seksjon 2. Kapittel 3
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