Learn Six Sigma in 4 weeks. Buy our Six Sigma Handbook 19.95$

- Six Sigma Tutorial
- Six Sigma DMAIC process
- Six Sigma Acceptance Sampling
- Sampling Plan Variation vs Lot Size Variation in Acceptance Sampling
- AQL Based Sampling Plans
- Decision Tree for Selecting Type of Variables in Sampling Plan
- FMEA – Failure Mode and Effects Analysis
- Types Of FMEA: Design FMEA (DFMEA), Process FMEA (PFMEA)
- The FMEA Quality Lever – Where To Put The Effort
- FMEA Quiz
- Six Sigma Confidence Intervals
- Confidence Limits
- Confidence Interval Formulas
- Z Confidence Interval for Means – Example
- t Confidence Interval for a Variance – Example
- Six Sigma Defect Metrics – DPO, DPMO, PPM, DPU Conversion table
- Fishbone Diagram – Fishbone Analysis
- Cost of Quality Defects and Hidden Factory in Six Sigma
- Pareto Analysis using Pareto Chart
- Six Sigma Calculators – DPMO, DPM, Sample Size
- How to select a Six Sigma project? Download selection grid template.
- How to create Six Sigma Histogram? Download Excel template
- Scatter Plots – Free Six Sigma Scatter Plot template
- How to create, use Six Sigma SIPOC tool? Download SIPOC Template
- Quality Function Deployment (QFD) – Download free templates
- What is Decision Matrix or Decision Making Matrix ?
- The nature of Process Variation
- What is RACI or RASCI Matrix/Chart/Diagram? Download free templates

Histograms are used to represent continuous data in the form of a diagram or chart. In the **Analysis **stage of DMAIC, Six Sigma histogram tools are used. Typically Histograms are represented as bar charts. Large amounts of data that is difficult to understand if represented in a tabular spreadsheet form.

In the **Measure **stage of DMAIC, the data is collected. Then this data is reviewed by the team. Typically the data collected is is of two types:

- Discrete data (true/false, fail/pass, success/failure )
- Continuous data (example: frequency, color, time). Histograms are best suited for representing this data.

Histograms can provide a visual display of such data by dividing this large data into a finite number of groups or buckets. Once the buckets are defined, you need to match and find out for every number what bucket it belongs to. Once a number is assigned to a bucket, you need to increment the frequency value of that bucket. Once all numbers are counted, you take the buckets and their frequencies and represent them in a bar chart with buckets on X axis and the the frequencies on the Y axis.

- Histograms are used to understand how the output of a process effects customer expectations
- They will help you find out if the process is capable of meeting customer requirements
- Histograms are graphs of a distribution (frequency of occurrence) of data.
- Histograms show centering, dispersion (spread), and shape (relative frequency) of the data.

Lets take the example of a part (a screw) which is manufactured at a plant. The ideal diameter of the screw is 52.3 mm. Lets measure the diameter of a random sample of 16 screws. The diameters are measured as below:

52.1 52.2 52 52.3 52.2 52.5 52.3 52.3 52.2 52.1 52.6 52.4 52.3 52.4 52.5 52.4

Lets group them into the following buckets:

52

52.1

52.2

52.3

52.4

52.5

52.6

Now lets count how many screws belong to each bucket and compute the frequency

Bucket | Frequency |

52 | 1 |

52.1 | 2 |

52.2 | 3 |

52.3 | 4 |

52.4 | 3 |

52.5 | 2 |

52.6 | 1 |

The above data can be represented as a bar chart as shown below:

In Microsoft Excel, you can create a histogram very easily using the “Analysis Toolpack” Add-In. (Go to File/Options/Add-Ins and make sure the Analysis ToolPak AddIn is installed). All you need to do is input your data (in our case all the diameters) into a sheet. You can use one single column or multiple columns. Also decide what your buckets are. Put them in a separate column. Now go to data menu and choose Data Analysis/Histogram. For the Input range, choose the appropriate Excel range containing the diameter data. For the Bin Range choose the column that contains your buckets. For the output, you can choose a range or a new sheet option. Click OK and Excel will automatically create the histogram table and Chart for you. No need to count and find out manually the frequency. Its done for you by the Analysis Pack histogram tool.

Download the Microsoft Excel (xlsx) Spreadsheet Template for Six Sigma Histogram

Additional information about six sigma histograms can be found at: isixsigma site, sixsigma study guide site.

Learn all the Six Sigma Concepts explained here plus many more in just 4 weeks. Buy our Six Sigma Handbook for only 19.95$ and learn Six Sigma in just 4 weeks. This handbook comes with 4 weekly modules. Eeach module has around 250 powerpoint slides containing six sigma concepts, examples and quizzes.