2.13
Graphique à barres multiples
Comme son nom l'indique, un graphique à barres multiples est similaire à un graphique à barres classique, mais comporte plusieurs barres permettant de…
Supposons que l’on veuille comparer le nombre d’étudiants et d’étudiantes inscrits dans différents cours : statistiques, biologie, physique et chimie. Une telle comparaison d’ensembles de données avec différentes catégories est visualisée à l’aide d’un graphique à plusieurs barres.
Ici, le graphique contient deux groupes de barres séparés par un espace pour indiquer deux ensembles de données.
Dans ce cas, les barres noires indiquent le nombre d’étudiants masculins et les barres sarcelle représentent le nombre d’étudiantes.
La première série de barres indique cinq étudiants et quatre étudiantes inscrits en statistique ; la deuxième série indique trois étudiants et cinq étudiantes inscrits en biologie, et ainsi de suite.
Dans les graphiques à plusieurs barres, on peut ajouter n’importe quel nombre de barres sous différentes catégories, en fonction du nombre donné d’ensembles de données.
Plusieurs graphiques à barres permettent de comparer et d’analyser les modèles entre plusieurs catégories. À partir de ce graphique à barres, on peut facilement répondre à des questions telles que quel jour a enregistré la plus grande vente de pommes ou quel est le fruit le plus populaire.
View the full transcript and gain access to JoVE Core videos
Q1: What is a multiple bar graph used for?
A multiple bar graph compares two or more sets of data across different categories. It displays multiple bars for each category, with each bar representing a different data value. This visualization helps identify patterns and answer comparative questions, such as which course has more female students or which product had the highest sales.
Q2: How do you read the axes on a multiple bar graph?
On a multiple bar graph, categories of different data types are listed along the horizontal x-axis, while frequency or data values are listed along the vertical y-axis. For example, when comparing student enrollment across courses, course names appear on the x-axis and the number of students appears on the y-axis. Bar heights directly correspond to the frequency values.
Q3: How many bars can you include in a multiple bar graph?
You can add any number of bars under various categories in a multiple bar graph, depending on the number of data sets you need to compare. However, each parameter must have the same unit of measurement. For instance, if comparing six students across four subjects, you would draw four bars for each student to represent their marks in each subject.
Q4: What is the difference between a bar graph and a multiple bar graph?
A bar graph displays a single set of data with one bar per category, while a multiple bar graph contains multiple bars per category to show relationships between different data values. Multiple bar graphs allow simultaneous comparison of two or more data sets, making them ideal for analyzing patterns across several categories with related information.
Q5: What are the limitations of using multiple bar graphs?
Multiple bar graphs often require additional explanation and may fail to expose key assumptions, causes, impacts, and underlying patterns. They can also be easily manipulated to give false impressions of the data. Despite their usefulness for comparison, these limitations mean they should sometimes be supplemented with other visualization methods for complete data analysis.
Q6: How do you organize data before creating a multiple bar graph?
Before creating a multiple bar graph, organize your data into a frequency distribution format with categories on one axis and corresponding values on the other. Ensure all parameters share the same unit of measurement. Group related data sets together so each category displays multiple bars side by side, making comparisons clear and patterns easily identifiable.
Q7: What types of comparisons can you make with a multiple bar graph?
Multiple bar graphs enable comparisons such as enrollment differences between male and female students across courses, sales variations of different products over time, or performance differences across multiple subjects for individual students. By analyzing bar heights within and across categories, you can identify trends, determine which groups are most popular, and compare relative magnitudes across data sets.