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Unit: Statistics
Chapter: Histogram & Box Plots
Reference: – Introduction to Histogram, Frequency Distribution and Class Intervals, Construction of a Histogram, Interpreting Histogram Shapes (Symmetric, Skewed, Bimodal), Introduction to Box Plot, Five-Number Summary (Minimum, Q1, Median, Q3, Maximum), Interquartile Range (IQR) and Outliers, Constructing and Interpreting Box Plots, Comparing Histograms and Box Plots
After studying this chapter, you should be able to understand:
- Introduction to Histogram & Its Need
- Frequency Distribution and Class Intervals
- Construction of a Histogram
- Interpreting Histogram Shapes (Symmetric, Skewed, Bimodal)
- Introduction to Box Plot & Five-Number Summary
- Interquartile Range (IQR) and Outlier Detection
- Constructing and Interpreting Box Plots
- Comparing Histograms and Box Plots
Pictograph:
A Pictograph is a graph that shows numerical information by using pictures, symbols or icons to represent data set. Each image stands for certain number of things. The advantage of using a pictograph is that it is easy to read. This is one of the simplest ways to represent statistical data.
Interpretation of Pictograph:
In interpreting a pictograph, we get a lot of information regarding the pictograph items.
Let us understand this with the help of an example. The following pictograph shows how many cars were washed at the washing center of a service station during 4 days of a week.
Source: Kapdec.com
We can get information from the pictograph easily by looking at it. We get to know total number of cars being washed on different days.
On Monday, 4×5 = 20 cars
On Tuesday, 5×5 = 25 cars
On Wednesday, 3×5 = 15 cars
On Thursday, 4×5 = 20 cars
We get to know by just looking at the graph that on Tuesday maximum number of cars were washed and minimum were on Wednesday.
Drawing a Pictograph:
There are various steps in drawing a Pictograph. Steps to form Pictograph are:
Step 1: Collect the data of the category you want to represent.
Step 2: Pick a symbol or a picture that accurately represents your data.
Step 3: One symbol cannot represent one frequency when the frequency of data is too high. You must set numerical value that one symbol will represent. This numerical value must be written along with the pictograph.
Step 4: Draw two columns that represent the category and the data. Then draw the actual symbol that represents the frequencies. The symbols can be drawn as fractions as well if the frequency is not a whole number.
Let us understand the steps with the help of an example.
Step 1: The following table shows the different ice cream making companies selling their ice-creams in the month of May.
Source: Kapdec.com
Step 2 & 3: Now let us use the symbol = 1000 ice cream sold.
Step 4: and then draw a pictograph for the above data, using the symbol as above.
Source: Kapdec.com
The above graph makes it is to understand the distribution of ice-creams of different ice-cream making companies. Ben and Jerry’s sells the highest number of ice-cream products and Dairy queen the lowest with 2000 ice-creams. We can find the answers to the questions by just looking at the pictograph.
Source: Kapdec.com
The above graph makes it is to understand the distribution of ice-creams of different ice-cream making companies. Ben and Jerry’s sells the highest number of ice-cream products and Dairy queen the lowest with 2000 ice-creams. We can find the answers to the questions by just looking at the pictograph.
