Statistics: Frequency and graphs

Lena traveled around Sweden all summer and saw all sorts of places. Small towns, big cities and the countryside. She wonders how many cities there are in Sweden. Where do most people live, and what is the average size of a city? Lina wants to know.

So she gets a list of all 290 municipalities in Sweden. and their population. To be fair, this is a list of municipalities, not urban centers but it'll do more for approximate calculations. The first thing Lina wants to know is the most common municipality size in terms of inhabitants. It turns out that no two municpalities have the same number of inhabitants.

So all municipalities are equally common or uncommon in terms of the population. So Lina arranges the population sizes into intervals, 10,000 inhabitants each. Then she calculates how many municipalities fall into each interval. There are 79 municipalities with fewer than 10,000 inhabitants, 91 with the number of inhabitants between 10 and 20,000, and so on. The number of municipalities in each interval is called the frequency, and this table is a frequency table.

A municipality with the greatest frequency or highest value in the second column has the most frequent size. To provide a visual representation Lina draws a bar graph. The y axis represents the number of municipalities within each interval. The x axis shows the number of inhabitants. Every bar shows how many muncipalities have a certain number of inhabitants.

It clearly shows that Sweden has mostly small municipalities and just a few large ones. Lina also depicts it in a pie chart. The whole circle represents all 290 municipalities. The size of each sector is proportional to the number of muncipalties in that interval. Pie charts are good for illustrating shares.

The whole circle is 100%. Therefore, it's easy to see that over a quarter of all municipalities have fewer than 10,000 inhabitants. In order to make the chart a little messy Lina decided to choose fewer intervals for this diagram. Here, the three largest cities are all in the same category. When dealing with large amounts of data, it can be hard to get an overview, interpret the information and make conclusions.

Tables help to clarify relations and find certain patterns. There are many ways to represent data. Two of them are, the bar graph, and the pie chart.