OC Curve Problem on Single Sampling - Sampling Technique - Metrology and Quality Engineering

TL;DR

The analysis demonstrates the process of drawing an OC curve for a single sampling plan, based on given data and probabilities of acceptance.

Transcript

hello students today let us solve a problem on oc curve so here in the question they are asking us to draw an oc curve from a single sampling so here the sampling is single sampling plan for n equal to 4000 that is the lot size and small n is the sample size which is given as 80 and c that is the acceptance number is 2 so first of all for the solut... Read More

Key Insights

• 🌱 An OC curve is a tool used in quality control to assess the effectiveness of a sampling plan.
• 💨 The Poisson's table helps determine the probabilities of acceptance for different combinations of np dash and c.
• 👻 The assumptions made about the process quality's range allow for a comprehensive analysis of the sampling plan's effectiveness.
• ❓ The OC curve starts from a probability value of 1 when the percent defective is 0.

Questions & Answers

Q: What is the purpose of drawing an OC curve for a single sampling plan?

The OC curve helps in assessing the effectiveness of a sampling plan by illustrating the relationship between the process quality (percent defective) and the probability of acceptance. It aids in making decisions about accepting or rejecting a lot based on sample inspection results.

Q: How is the probability of acceptance calculated from the Poisson's table?

The probability of acceptance is obtained by referencing the Poisson's table, which provides values based on the np dash (product of process quality and sample size) and the acceptance number (c). The table helps determine the probability of acceptance for different combinations of np dash and c.

Q: Why is the assumption made that the process quality varies from 0 to 9 percent?

The assumption allows for a range of process quality scenarios to be considered. By assuming a varying process quality, the OC curve can capture the different probabilities of acceptance at different levels of percent defective in the lot.

Q: How is the OC curve plotted?

To plot the OC curve, the calculated probabilities of acceptance for different percent defective values are marked on the y-axis. The corresponding percent defective values are marked on the x-axis. These points are then connected to create the curve, which represents the relationship between percent defective and probability of acceptance.

Summary & Key Takeaways

• The content explains how to draw an OC curve for a single sampling plan, using given parameters such as lot size, sample size, and acceptance number.

• The process quality is assumed to vary from 0 to 9 percent, and the probabilities of acceptance are calculated using a Poisson's table.

• The calculated probabilities are plotted on an OC curve, which shows the relationship between the percent defective and the probability of acceptance.