# Dot Plots

A **Dot Plot** is a graphical display of data using dots.

### Example: Minutes To Eat Breakfast

A survey of "How long does it take you to eat breakfast?" has these results:

Minutes: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |

People: | 6 | 2 | 3 | 5 | 2 | 5 | 0 | 0 | 2 | 3 | 7 | 4 | 1 |

Which means that 6 people take 0 minutes to eat breakfast (they probably had no breakfast!), 2 people say they only spend 1 minute having breakfast, etc.

And here is the dot plot:

You can create your own dot plots.

Another version of the dot plot has just one dot for each data point like this:

### Example: (continued)

This has the same data as above:

But notice that we need numbers on the side so we can see what the dots mean.

## Grouping

### Example: Access to Electricity across the World

Some people don't have access to electricity (they live in remote or poorly served areas). A survey of many countries had these results:

Country | Access to Electricity (% of population) |
---|---|

Algeria | 99.4 |

Angola | 37.8 |

Argentina | 97.2 |

Bahrain | 99.4 |

Bangladesh | 59.6 |

... | ... etc |

But hang on! How do we make a dot plot of that? There might be only one "59.6" and one "37.8", etc. **Nearly all values will have just one dot.**

The answer is to **group the data** (put it into "bins").

In this case let's try rounding every value to the nearest 10%:

Country | Access to Electricity (% of population, nearest 10%) |
---|---|

Algeria | 100 |

Angola | 40 |

Argentina | 100 |

Bahrain | 100 |

Bangladesh | 60 |

... | ... etc |

Now we count how many of each 10% grouping and these are the results:

Access to Electricity (% of population, nearest 10%) | Number of Countries | |
---|---|---|

10 | 5 | |

20 | 6 | |

30 | 12 | |

40 | 5 | |

50 | 4 | |

60 | 5 | |

70 | 6 | |

80 | 10 | |

90 | 15 | |

100 | 34 |

So there were 5 countries where only 10% of the people had access to electricity, 6 countries where 20% of the people had access to electricity, etc

Here is the dot plot:

Percent of Population with Access to Electricity

And that is a good plot, it shows the data nicely.