A Block Diagram is used to assess the effect of input variables or factors on your output (or response). First, identify any factors that could have a significant impact on your response variable. Learning how to draw a block diagram is a lot easier than it sounds and can be learned quickly.

In a designed experiment, blocks can be used to handle uncontrolled factors that are generally considered “noises, having undesired influence as a source of variability. For example, a block can be used to handle humidity as an undesired “noise factor” that can influence the results but cannot be directly controlled by the experimenter.

You want to get the most from your experiment by minimizing the influence or noise of other factors in your environment that are not relevant to your research.

You want to know the effects of temperature, machine speed, and pressure on the lamination integrity of a sheet of glass. You should measure your glass sheet under the same experimental conditions to minimize other factors. You will need to perform your experiment in each of the three shifts that the plant operates.

A nuisance factor is one that you think has an effect on the response but which you don’t care about right now. It is important to minimize the amount of variability it transmits to your response. Some of the most common nuisance factors are operators, batches of raw material and pieces of test equipment.).

These are the conditions under which you might use randomization or blocking:

  • You can use blocking if the nuisance factor is controlled and known.
  • You would label the nuisance factor if it is uncontrollable and unknown. Randomization would be used to balance the effect of the nuisance factor across the experiment.

The rule of thumb is to block anything you can, and randomize what you cannot. If it is impossible to keep the nuisance factor constant through all the experiments, blocking should be used.

Block diagrams are high-level flowcharts that can be used in engineering, hardware, electronic, and software design. It can be used to create new systems or to improve existing ones. A block diagram shows, at a drawing level how a process flows within an establishment from function to function, or unit to unit. This diagram uses blocks to represent the essential activities and connects them by connecting lines that represent elements or communication flows.

How to make a Block diagram:

Block is a description of the logical as well as physical components of the system.
Part: It includes all aspects that are modeled using association or aggregation.
Reference: It contains all components that were created using association and aggregation.
Standard Port is the interface point between a system block, and an identical environment.
Flow Port : represents the point of interaction where a block can emerge.

The Block Diagram: Block Diagram helps to understand the process. It shows all parts and how they interconnect in a simple format. Block diagrams are useful tools for both designing new processes and improving existing ones. The diagram should provide a quick, visual view of the work, and help to identify process points of interest.