A **box plot** is a graph that shows the frequency of numeric data values. It can be drawn either horizontally or vertically. It is referred to as a Box-and-Whisker Plot as it displays the data in a box-and-whiskers format. Box plots are widely used in statistics, scientific research, higher education, process improvement, and in social and human sciences.

# Category Archives: Understanding Cause and Effect

# Histogram

A **histogram** is a graph which shows the frequency of continuous data values. It is a type of bar chart that can be drawn either vertically or horizontally. Histograms are widely used in statistics, process improvement, scientific research, economics, and in social and human sciences.

# Graphical Analysis

Graphing the data can be utilized for both historical data already available and when analyzing the data resulting from live data collection activities. Of course, you need to pick the right graphical tool as there are a lot of different ways to plot your data. A number of commonly used graphical tools will be covered here. However, note that if one graph fails to reveal anything useful, try another one.

Read more »# Normal Distribution

Continuous distributions describe variables that take values from a continuous range and can be measured with any degree of accuracy. The commonest and the most useful continuous distribution is the normal distribution. The **Normal Distribution** is a symmetrical probability distribution where most results are located in the middle and few are spread on both sides. It has the shape of a bell and can entirely be described by its mean and standard deviation. Read more »

# Probability Distributions

Most improvement projects and scientific research studies are conducted with sample data rather than with data from an entire population. A **Probability Distribution** is a way to shape the sample data to make predictions and draw conclusions about an entire population. It refers to the frequency at which some events or experiments occur. It helps finding all the possible values a random variable can take between the minimum and maximum statistically possible values. Read more »

# Descriptive Statistics

Descriptive statistics are methods of describing the characteristics of a data set. It includes calculating things such as the average of the data, its spread and the shape it produces. It involves describing, summarizing and organizing the data so it can be easily understood. Graphical displays are often used along with the quantitative measures to enable clarity of communication. Descriptive statistics helps exploring and making conclusions about the data in order to make more rational decisions. Read more »

# Relationship Mapping

A **Relationship Map** is a visual display that shows the relationships between individual items. It allows to see and analyze the logical links between the different elements of any situation. A simple example of a relationship map is your network of personal and social relations. Another example is what is called the **Interrelationship Digraph** which is a visual display of the cause and effect relationships involved in a process or problem. Read more »

# Matrix Diagram

A **Matrix Diagram** is a table that allows sets of data to be compared in order to make better decisions. It displays the existence and strength of relationship between pairs of items of two or more sets. The relationship is then indicated by a number or symbol in each cell where the two items intersect in the matrix. A matrix diagram can be used as part of other decision making tools. Cause and Effect Matrix and Quality Function Deployment are examples of tools that use the matrix diagram. Read more »

# Fishbone Diagram

Sometimes it is difficult to spot problems and only symptoms will be acted on leaving the real causes intact. This indicates lack of information and poor understanding of the problem and leads usually to a weak solution. A **Fishbone Diagram** is often used to identify and organize the potential causes of a business problem in an easy and understandable format. It is used to identify the sources of process variation which caused the problem to occur. It is called this way because of its shape that looks like a fishbone. It is also called **Ishikawa Diagram** and **Cause and Effect Diagram**. Read more »

# Scatter Diagram

Many situations require the investigating whether a relationship exists between two or more variables. A line manager, for example, may want to check the relationship between the number of training hours and employee productivity, or if the number of defects is a function of the experience of the person causing it. A call center manager may be interested in studying the relationship between the number of people working on a shift and the average answer time.

Read more »# SIPOC Analysis

A **SIPOC Map** is high-level summary of the process. It provides a big picture view of the important elements of the process to gain deeper understanding of the context in which the process occurs. SIPOC is an acronym that stands for Suppliers, Inputs, Process, Outputs and Customers.

# Histograms and Boxplots

Histograms and boxplots are graphical representations for the frequency of numeric data values. They aim to describe the data and explore the central tendency and variability before using advanced statistical analysis techniques. In this article, we will further discuss the similarities and differences between these two tools.

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