1, average value: a set of data, divided by the total score, the number is the average value of this set of data. The size of the average is related to each data in a set of data, and the change of any data will cause the change of the average, that is, the average is affected by a larger number and a smaller number.

2. Median: arrange a group of data in order of size, and call a number in the middle position (or the average of two numbers in the middle position) as the median of this group of data. The size of the median is only related to the arrangement position of the data. So the median is not affected by the size of the number. When the individual data in a group of data changes greatly, it is often used to describe the centralized trend of the group of data.

3. Mode: The data with the highest frequency in a group of data is called the mode of this group of data. Therefore, looking for a set of data patterns does not need to be calculated or sorted, but only needs to count the frequency of data with more occurrences. There is a close relationship between mode and probability. The size of a pattern is only related to some data in a set of data. When a set of data is repeated many times, its pattern is often the concentrated trend we care about.