Bar charts have three elements: number of groups, group width and group limit.
1, number of groups: divide the data into several groups, and the guiding experience is to divide the data into 5~ 10 groups.
2. Group width: the width of each group is the same. The choice of group number and group width is not independent, and an empirical criterion is: approximate group width = (maximum-minimum)/group number.
Then determine the initial approximate group width according to rounding, and then adjust it according to the data situation.
Bar charts are suitable for:
Bar charts are mainly used to represent discrete data, that is, counting data.
The similarity between a single bar chart and a composite bar chart is that people can clearly see the quantity. The difference is that a single bar chart is used to compare one object, while a double bar chart is used to compare the number of multiple objects.
When the number of repeated experiments n increases gradually, the frequency fn(A) shows stability and gradually stabilizes at a certain constant, which is the probability of event A. This "frequency stability" is also called statistical regularity.
Frequency is not equal to probability. According to Bernoulli's theorem of large numbers, when n approaches infinity, frequency fn(A) approaches probability P(A) in a certain sense.
Histograms are also called histograms and mass distribution maps. It is a statistical report chart, which shows the data distribution with a series of vertical bars or line segments with different heights. Generally, the horizontal axis represents data type and the vertical axis represents distribution. The significance of histogram method in quality management, how to predict and monitor the quality of products?
How to analyze the quality fluctuation? Histogram is a tool, and it is clear to deal with these problems graphically. It reflects the distribution of product quality by processing the seemingly disorderly data collected, and judges and predicts the product quality and unqualified rate. Histogram, also known as mass distribution map and histogram, is the main tool to display data changes.