Drawing Charts

Tools of Quality? Histograms Frequency Graph Bar Chart Pie Chart Line Graph Scatter Plots Control Charts Basic knowledge for anyone interested in quality, engineering problem solving & systems design E O Jones

Histogram # times ordered Slices of Pizza In statistics, a histogram is a type of graph that shows the distribution of frequencies of data, usually in the form of vertical bars. This type of graph is also commonly called a frequency histogram. In a histogram graph, the height of each bar shows the number of items that fall into that range on the graph. # times ordered Helpful in showing orders frequencies and variation. Slices of Pizza E O Jones

What is the difference between a bar graph and a histogram? In bar graphs are usually used to display "categorical data", that is data that fits into categories. For example suppose that I offered to buy donuts for six people and three said they wanted chocolate covered, 2 said plain and one said with icing sugar. Histograms on the other hand are usually used to present "continuous data", that is data that represents measured quantity. The data would then be collected into categories to present a histogram. Histograms are used to show the different frequencies in a process. It is useful for identifying trends and relationships that can lead to quality improvements. E O Jones

Frequency Polygon Easy to draw, just put a mark at the top (in the middle) of each bar and join with straight lines. Good for comparing sets of data E O Jones

Number of grade ‘C’ or above passes in maths (B band) x 32 28 24 20 16 12 8 4 1999 2000 2001 2002 2003 2004 2005 F R E Q U N C Y x x x x x x YEAR E O Jones

A bar graph E O Jones

How Is the Information Presented? A bar graph is made. E O Jones

A pie chart E O Jones

Interpreting Pie Charts In a Mozambique village 324 litres of water are used each day. The pie chart shows how the water is used. Cooking Washing themselves Washing clothes Washing pots For animals E O Jones

Cooking Washing themselves Washing pots Washing clothes For animals Activity Angle Cooking Washing themselves Washing clothes For animals Washing pots 90 90 Cooking Washing themselves Washing pots Washing clothes For animals E O Jones

Cooking Washing themselves Washing pots Washing clothes For animals Activity Angle Cooking Washing themselves Washing clothes For animals Washing pots 90 90 72 54 54 Cooking Washing themselves Washing pots Washing clothes For animals E O Jones

A line graph E O Jones

A pictograph Chocolate Vanilla Strawberry Mint & Chip Rocky Road Bubble Gum E O Jones

Scatter Diagrams Positive Correlation Negative Correlation No Correlation Positive Correlation? Negative Correlation? E O Jones

Control Charts 17 inches 16 inches= Upper Limit Lower Limit 15 Inches X 16 inches= Monitoring the pizza process, this example shows how almost every pie is within specifications. The process should be analyzed to discover why the one small pie was produced and corrected to improve quality. Small Pie E O Jones