Statistics • Organizing and Graphing Data
Enter raw quantitative data and this tool will build a grouped frequency distribution, including class boundaries, class width, class midpoint (mark), relative frequency, percentage, and graphs (histogram, frequency polygon, and a smoothed frequency curve).
A grouped frequency distribution summarizes numerical data by splitting the number line into class intervals and counting how many observations fall in each class. It is useful when the dataset is large and a compact table is needed.
Fewer classes give a smoother, simpler summary but may hide structure, while more classes show more detail but can look noisy. If you leave the number of classes blank, the calculator selects an automatic value that is typically in a reasonable range.
Class limits are the stated endpoints of each class interval, such as 801 to 1000. Class boundaries adjust endpoints to remove gaps between adjacent classes on a continuous scale.
Relative frequency is f / N, where f is the class frequency and N is the total number of observations. Percentage is (f / N) x 100, so percentages across all classes add up to about 100% (allowing for rounding).
A histogram shows class frequencies using adjacent bars. A frequency polygon connects points plotted at class midpoints to show the distribution shape, and the smoothed frequency curve is a rounded version of that overall shape.