Calculadora de Distribuição de Frequência
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
F_ac(k) = Σ f_i (i=1..k)
About this calculator
The Frequency Distribution Calculator is a tool that organizes a dataset into classes or intervals, calculating the absolute frequency (number of observations in each class) and the cumulative frequency (sum of frequencies up to that class). It is useful for summarizing large volumes of data, making it easier to visualize the distribution of values. The operation is simple: you enter the raw data (separated by commas or spaces) and define the number of classes or the desired interval. The calculator then groups the data, counts the occurrences in each class, and calculates the cumulative frequency progressively.
The formula used is F_ac(k) = Σ f_i, where f_i is the absolute frequency of class i, and the sum goes from i=1 to k. For example, if the first class has 5 observations and the second has 3, the cumulative frequency up to the second class is 8. This tool is ideal for students and professionals who need to analyze data in areas such as statistics, market research, quality control, and social sciences. It helps identify patterns, such as concentration of data in certain ranges, and serves as a basis for constructing histograms and frequency polygons.
When to use? In situations such as analyzing class grades, income distribution, population ages, or any numerical dataset that needs to be summarized. Common precautions: choose an appropriate number of classes (too many classes can fragment the data, too few can hide details), ensure that intervals are mutually exclusive and of equal width, and verify that the data is correct before entering. Additionally, cumulative frequency is useful for calculating percentiles and quartiles.
Frequently asked questions
How to choose the ideal number of classes?
A common rule is to use the square root of the number of observations (√n) or Sturges' rule: k = 1 + 3.3 * log10(n). The important thing is that classes have the same width and cover the entire range of data.
Does the calculator work with decimal data?
Yes, it accepts decimal numbers (use a dot as decimal separator). Just make sure the data is in the correct format, separated by comma or space.
What is cumulative frequency and what is it used for?
Cumulative frequency is the sum of the frequencies of previous classes up to the current class. It is used to know how many observations are below a certain value, useful for calculating percentiles and constructing graphs like the ogive.
Can I use this calculator for grouped data?
Yes, you can enter the class limits and frequencies directly if you prefer. The calculator also allows raw data input to generate the distribution automatically.
What is the difference between relative and cumulative frequency?
Relative frequency is the proportion of observations in each class (absolute frequency divided by total). Cumulative frequency is the sum of absolute frequencies up to the class, indicating the accumulated total.