Viewing the distribution of data over intervals with a histogram

This example shows how to make a histogram to the distribution of data over intervals, using weather data from Qlik DataMarketas an example.

Dataset

In this example, we'll use weather data loaded from the Weather for more than 2500 cities worldwide data source in Qlik DataMarket. The dataset is based on the following selections in Qlik DataMarket:

  • Location: Sweden > Gällivare Airport
  • Date: All time
  • Measurement: Average of the 24 hourly temperature observations in degrees Celsius

The dataset that is loaded contains a daily average temperature measurement from a weather station in the north of Sweden during the time period of 2010 to 2017.

Visualization

We add a histogram to the sheet and add the field Average of the 24 hourly temperature observations in degrees Celsius as dimension.

The visualization creates a frequency measure automatically, and sorts the temperature measurements into a number of bars according to frequency distribution.

We can adjust the size of the bars to get even intervals, by setting Bars to Custom and Bar width (x-axis) with a width of 5. This adjusts the bars to be intervals of 5 degrees Celsius as shown below:

Histogram with the dimension Average of the 24 hourly temperature observations in degrees Celsius.

Discovery

The histogram visualizes the frequency distribution of the temperature measurements. You can hover the mouse over a bar to see more details of the frequency.

We can see that most days, the temperature is between -5 and 15 degrees Celsius. There are days below -30, but they are not many.

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