Statistics Basics: Changing Data Counts to Percent
When working in statistics we begin by collecting counts of distinct types of data which are usually displayed in tables for analysis or creating charts. It can be helpful to turn those count into percentages for further analysis depending on what you are trying to learn. Below is a table with the data from the Titanic’s fatal voyage. It includes the totals (row 4) for each passenger class count; first, second, third; as well as the crew complement along with the number in each group who survived or died along with those totals in column F.
For our purposes, we want to know the percentage in each group that survived or died as well as the overall percentages. to convert to percent, we will need to do some simple math with the numbers.
Beginning with the 1st class column, to find the percent of survivors divide 203 the number of survivors by 325 the total number of passengers in 1st class. 203 ÷ 325 = .625 or 62.5% of 1st class passengers survived the sinking of the Titanic. You can do the same with the dead; 122 ÷ 325 = .375 or 37.5% died. For each group in the table you would divide the alive or dead by the total for that group to get a new table with percentages. The completed table is shown below.
When we make a Pie chart of the tables we have the actual percentages available to compare with the chart itself. Below is the Pie Chart for those who were Alive after the sinking of the Titanic in each group. I have added in the actual percentages for each group using text boxes.
By changing the data from counts to percent we can see glaring differences in the survival rates between the groups. Using percent is just another way to analyze what is happening in the collected data but it is important to understand that percent is a tool that will work in some situations and not in others. By changing the form of the data, we can look at different trends and analyze the data for a better understanding those trends.