Based on ideas of Peter Sedlmeier
The frequency grid offers an intuitive transition from frequencies to concepts of probability and conditional probabilities.
Example
A pond contains 170 fish, represented by blue cells. In a first catch 75 fish are caught and returned, marked with a cross, to the pond. The fish caught in the second catch are marked with a circle. There are 6 marked fish in the second catch.
The results can be presented in two ways: as a frequency tree or a cross table. You can change the order of the frequency tree with a button and put percentages in the tree. In the cross table you can show either numbers or percentages.
We might ask the question whether fish which have been caught before have a higher probability of being caught again. Do fish have a “catch memory”. ?
The grid
The grid consists of cells. The number of cells is determined by the number of rows and columns
Marking cells
A cell of a frequency grid may be left blank, or colored blue, green or white. (These options are alternatives: they cannot be used together.) A cross and a circle can be used singly or together. These marks are used for attributes and should be given names. You place colors or marks on the grid by first choosing the color/mark and then clicking on a cell.
Buttons
Names
Colors have a name because they should represent some feature. The cross and circle marks can be used simultaneously, therefore there are names for being either present or not present.
Sort
The marks are sorted so that it is easy to count them.
Comments
An explanation of the situation, or background information to the frequency grid, can be entered here. The comments are saved together with the grid and can be edited or expanded later.
Randomize
The marks are distributed randomly on the grid.
Frequency tree
Overview of the results in the form of a tree.
shows the views one by one.
writes the changes in percentages.
Cross table (contingency table)
A cross table, or contingency table, is two-dimensional. With the pull-down menus you can show the different categories. The numbers can be shown absolutely or relatively in several ways.
You can save, open and print the frequency-grid which you have created or modified.