How Reliable Is Reliable

Assignment -1

“How reliable is Reliable”

“Our Quality Control is superb. We do check the quality at each phase of the production. Of all the ICs we produce, only 5 out of every thousand are defective and this is based on this year's data", said Mukund Roy, He is the HR Manager, Production of the BS World Semiconductors (BSWS). "Do you test these ICs before dispatch to the client?" asked Naveen.

Naveen is representing Reliable Devices (India) Limited (They always say "Reliable is reliable"). His company has developed, recently, a device and an associated testing procedure for the ICs. "As I said, we check the quality at each stage. There is no reason for testing them again", replied Mukund. "Only 0.5% of our ICS are returned from our customers and we always take care of them. But, of course, if your device is 'fail safe', we may decide to avoid the costs involved in handling the defectives. How reliable is your system?"

Naveen is happy for the opening he got. He had done his home-work, thanks to the access provided by the company during his earlier visits. “Yes”, he said. "I have tested your ICs on our device using our procedure, let’s call it our system. The results are very encouraging. We collected 200 ICs which were returned by your customers as defective, and tested them using our System and our system was able to diagnose all but 2 of them as defective. Of course, we tested the ones which are certified as non-defective, about 160 of them and, get this; all but 8 were accepted by our system as good as gold. I agree, our system is not absolutely accurate but it is as absolutely accurate as ever possible. We always say “Reliable is reliable", said a confident Naveen, "It takes only 2 minutes to mount and test each IC."

Mukund quickly did some calculations. Their ICs are used by many customers and they go into many end products. The customers don't bother to test the ICs before they are used. This is because of the company policy that not only the IC is replaced; free of cost, but the entire cost incurred by the customer because of the defective IC is also reimbursed, The Finance people have always been complaining about the accuracy of these costs as estimated by the customers. If we can catch the defectives before they are shipped out... Mukund is thinking.

But is Reliable really reliable?

Assignment-2

1. An engineer measured the Brinell hardness of 25 pieces of ductile iron that were subcritically annealed. The resulting data were:

168 165 174 178 179

156 163 158 184 156

183 178 174 178 169