This is an evident fact that for any industry to grow, it has to constantly improve its processes and quality parameters. This becomes more important in case of highly regulated and constantly advancing industries such as pharmaceutical industry. There are many tools and methods available to identify, investigate, assess and solve quality problems. But there are seven basic quality control tools that are widely used by all types of industries including pharma. They are popularly known as “7 QC tools” or “Seven Basics Tools of Quality”.

These 7 QC tools are used for collection, collation, analyzing, interpretation and reporting of data. The data thus reported is used for identifying various issues that are currently or may in future may affect the product quality. The reported data is also used for improving the processes. These rules are called as basic as the person with basic or very little understanding of statistics can apply the tools and they can be used to solve variety of quality related concerns.

 

The Seven basic tools of quality are as follows:

  1. Cause and Effect Diagram (Ishikawa or Fishbone diagram)
  2. Check sheet
  3. Control Charts
  4. Histogram
  5. Pareto Chart
  6. Scatter Diagram
  7. Flowchart

 

  1. Cause and Effect Diagram (Ishikawa or Fishbone Diagram): Kaoru Ishikawa is credited with introduction of this method; hence, it is also known as Ishikawa diagram. The shape of diagram also represents the skeleton of a fish and hence most popularly called as fish bone diagram.

The principle of cause and effect diagram is to identify various factors or causes which may lead to an effect or problem. The use of cause and effect diagram helps to identify all the probable factors that could lead to an effect. The probable causes are categorized into 6 main branches identified as 6M’s namely:

    1. Man
    2. Machine
    3. Material
    4. Method
    5. Measurement
    6. Mother Nature (Environmental Factors)

 

Some experts identify two more causes namely:

    1. Management
    2. Maintenance

All the probable factors are identified through brain storming and are categorized into above main categories. All the probable causes are then assessed individually to identify the root cause of the issue. The probable causes are evaluated and are arranged in the sequence of likelihood to cause an effect. The factor which is observed to be the one leading to the effect is often designated as root cause. Sometimes more than one root causes may also be identified.

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The head of fishbone diagram represent the effect and the extensions on the left represent causes. The fishbone diagram helps to list all the factors.

Advantages of Cause and Effect diagram:

    1. Extensive brainstorming sessions leads to identification of numerous probable causes.
    2. Decrease the probability of duplication of causes in same diagram.
    3. All causes can be viewed simultaneously.
    4. Cross-functional teams doing brainstorming leads to broad thinking and bring many relevant issues on the table for the management to take action.
    5. It helps in prioritizing the causes.

 

Disadvantages of Cause and Effect diagram:

    1. Too much of brainstorming may lead to inclusion of many irrelevant potential factors as causes. Too much clutter results in wastage of time and resources.
    2. Sometimes brainstorming may leads to listing of the causes which are based more on ‘beliefs’ than evidences.
    3. Complex Interrelationships between multiple causes are not easily distinguishable on fishbone diagram.

 

  1. Check Sheet: The check sheet is one of the simplest tool out of 7 QC tools. It is basically a sheet for performing date collection. The data collection is done in real time and from the same location where it is being generated. Both qualitative as well as quantitative data is collected using check sheet. The check sheet used for collecting quantitative information, is also called tally sheet.

This check sheet helps to collect and tabulate the actual data which may help in identification of the cause to a problem which could have been affecting the firm for a long time. It also helps in checking the frequency of the problem.

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It helps to quantify defects by location, type of defects etc. Checklists are flexible and can be modified as per required information.

Advantages of Check Sheets:

    1. Easy and convenient application
    2. Provides clear and easily processable data

 

  1. Control Charts: Variability is considered intrinsic in any kind of manufacturing process. The variability in a process may occur due to Random cause (Unpreventable) and Assignable Cause (Preventable cause).

Control charts helps to assess that if the measured parameters are under the state of control and are meeting their predefined specifications.

In a control chart data is plotted against the time on X-axis. A central line on the y-axis indicates mean, the line above the middle line indicates upper control limit and the line below the middle line indicates lower control limit. These lines are based on historical data and sometimes they represent the regulatory or guidelines specifications also.

This tool helps to identify any Out of Specifications (OOS), Out of Trends (OOT) and process capability over a period of time.

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Sample control chart for illustration purpose only where in pH range is 5-7. Hence, Lower Control Limit (LCL) is 5 and Upper Control Limit (UCL) is 7.

 

  1. Histogram: Histograms are most commonly used bar graphs for displaying frequency distribution. It helps in prioritizing issues and identify the areas requiring immediate attention.

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As illustrated in the histogram chipping is a tablet defect which is most frequent. It indicates the area which is a priority and requires immediate attention of the process engineers to improve the process and decrease the number of a particular defect.

 

  1. Pareto Chart: It is based on 80-20 rule. If applied to manufacturing process, it can be simply understood as 20% of factors are responsible for 80% of manufacturing defects. Pareto chart is a special type of histogram which includes both bars and line graph. The bars are arranged in descending order of their occurrence and the cumulative total is shown by line graph.

In pareto chart, items are arranged in the order of the extent of their contribution to the defects. The tool is used for identification of the factors which shall be prioritize first to solve maximum defects as it is responsible for majority of defects. It helps to differentiate between few important factors from many minor issues.

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As illustrated in the pareto chart, maximum number of deviations are done by manufacturing department. As manufacturing is responsible for almost 80% of deviations, hence, appropriate corrective and preventive actions in manufacturing shall drastically reduce the number of deviations.

 

  1. Scatter Diagram: This tool is used to understand the dependence of two variables on each other. In scatter diagram independent variable is plotted on x-axis and dependent variables are plotted on y-axis. It helps to understand the relationship profile between two variables which can be positive or negative or non-linear etc. It also helps to understand if the two variables are at all dependent on each other.

 

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  1. Flowchart: It is a diagram that represents process flow using various symbols to indicate the process flow. Flowchart indicates process inputs, decision steps and process outputs using various types of boxes. All these boxes are connected using arrows to depict the flow of process. Flowcharts are prepared to analyze or design a process or program. It helps to identify any potential problem in a process or program. This is important to note that some lists replace flowchart with stratification or run-charts.

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