# Data Visualization Principles (Data Analytics)

> Choosing the right chart, data storytelling, Tufte's principles, data-ink ratio, colors, context, visual hierarchy, misleading charts

- 20 interview questions
- Junior
- [Interview Questions: Data Analytics](https://sharpskill.dev/en/technologies/data-analytics/interview-questions.md)

## 1. Which chart type is best suited for comparing values across different categories?

**Answer**

The bar chart is the most effective chart for comparing values across distinct categories. The human eye is very efficient at comparing lengths aligned on a common axis, making the reading intuitive. Bars can be vertical or horizontal depending on the number of categories and label length.

## 2. Which chart type is best suited for showing how a value changes over time?

**Answer**

The line chart is the standard choice for visualizing time-based trends. The line connects data points chronologically, making trends, cycles, and anomalies immediately visible. Unlike bar charts, line charts emphasize continuity and the direction of change rather than individual values.

## 3. What is the main drawback of a pie chart?

**Answer**

The main flaw of pie charts is that the human eye struggles to compare angles and areas. Beyond 3-4 categories, it becomes nearly impossible to distinguish proportion differences. Edward Tufte recommends always preferring a bar chart or data table over a pie chart, except in rare cases where only the part-to-whole relationship matters.

## 17 more questions available

- What is the data-ink ratio as defined by Edward Tufte?
- Which chart type should be used to visualize the relationship between two numerical variables?

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## Other Data Analytics interview topics

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