Attribute Data vs Variable Data / Discrete Data vs Continuous Data

Introduction

 - Measurement System Analysis study and Control chart selection decided based on collected data i.e attribute data (Discrete) or Variable data (Continuous).

 - This plays major role in problem solving process.

Attribute Data

 - It is a qualitative data that focuses on numbers for recording and analysis like yes or no.

 -  Attribute data simply classifies the output data as defective or not defective or pass/fail.

 - This data is simpler to gather than variable data.

 - Attribute data has two types

1. Yes/No type

 - Product confirmation - it is ok or not ok

 - Student pass the exam or fail the exam.

 - Machine Condition - running or not running

2. Number type

 - Number of defective parts in a lot

 - Number of employee in organization.

 - How many students failed the exam?

Benefits of Attribute Data

 - Attribute data is useful when qualitative information is required.

 - It is useful to create ratios, percentage or charts.

 - P chart, np chart, u chart, c chart used in attribute data

Variable Data

 - It is focus on measurements of system.

 - Variable data provide detailed and concrete information.

 - For example, if one product need to be made a one inch specification. at this stage attribute data only state whether each product fit the specification or not.

But variable data provide detail specification of each product. 

 - Example of variable data is 

1. Length, height, width of product. 

2. Weight of product

3. ID, OD of the component.

Benefits of Variable Data

 - Variable data provide detailed and concrete information.

 - Variable data is more useful while measuring the quality of the product.

 - X bar chart, R bar chart, X-MR chart etc. are used in variable data.