# What are misclassified instances in data and how to calculate it?

I am doing assignment of Data mining , and stuck on one thing book i am following is "introduction to data mining" by viper kumar , it is "How many instances are misclassified in given decision tree?"

Tree:

     True---------+ A+---------------False
|                               |
|                               |
|                               +
+----+------+              True-----+B+-------False
|           |              |                  |
|  +(25)    |              |                  |
|           |              +                  |
|           |              C               +--+----------+
+-----------+              +               |             |
|               |  -(30)      |
True------+------False    |             |
|                |        +-------------+
|                |
|                |
+------+--+          +--+-------+
|         |          |          |
| -(20)   |          | +(25)    |
|         |          |          |
+---------+          +----------+


i am wondering how to calculate it.

Note: i am not asking for solution rather the concept behind it.

• Welcome to CV. Rather than providing a link and leaving it up to the readers to figure your precise question out, it would be much better to spell it out in your statement. Please revise your query to reflect this. Mar 29 '16 at 13:56