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A false alarm, occasionally maybe okay or one may never want it similarly a missed alert may not be acceptable or sometimes it can be lived with. Too many false alarms can lead to unwarranted changes in a perfectly stable process and might lead to defects being produced at a later time, and at the same time missed alert means that the defective product will reach the customer which would have business impacts. In statistical terms, one can say that a false alarm is like a Type I error, and a missed alert is like a Type II error. As in the case of type I and type II errors, it largely depends on the consequences of these alarms which would help one decide which is more critical. Personally I would prefer a false alarm over a missed alert, as a false alarm will give opportunity to the operator / process engineer to study the cause of the alarm and then only he would take action on the process, however a missed alert passes on the fault to the next step, and the chances of the defect reaching the customer is high. Thanks Jisha Nair

Background and Concept: False Alarm and Missed Alert are better understood with the two types of errors that are possible in statistical Hypothesis testing. Dealing with them with reference to test of hypotheses will provide more insights than otherwise. Any hypothesis test is begun with the assumption that the null hypothesis is correct. Null hypothesis is the default position and corresponds to the idea that "one is innocent until proven guilty". False alarm or Type I errors or False Positives (α): They happen when we reject a true null hypothesis. Missed alert or Type II errors or False Negatives (β): They happen when we accept (fail to reject) a false null hypothesis. Which error will you prefer over the other? The answer to this question depends on the problem and the worst that could happen if either a Type1 or Type 2 error was committed. Example 1: Person accused of Murder awaiting Death Sentence. Null Hypothesis: Person did not commit murder. Type 1 error: Person did not commit murder but pronounced guilty. (Rejected true Null Hypothesis) Type 2 error: Person committed murder but pronounce Not guilty. (Accepted false Null Hypothesis) In this example, though Type 2 error is not favorable to society, but hanging an innocent person is far worse. So Type2 error or a Missed alert is preferable. Example 2: Person being screened for a disease to prescribe further tests. Null Hypothesis: Person does not have the disease. Type 1 error: Person does not have the disease but recommended for further tests. (Rejected true Null Hypothesis) Type 2 error: Person has the disease but recommended for no further tests. (Accepted false Null Hypothesis) In this example, Type 1 error might cause the patient to undergo further tests but might finally reveal that he does not have the disease. A type 2 error would prevent a legitimate patient from undergoing further tests. But a legitimate patient can re-do the test if the symptoms persist, and it is fine for a person to do some further tests even if he does not have the disease. So Type1 error or False alarm is preferable. Example 3: Person being screened for a disease (presence of which has a good rate of survival and normal life) to prescribe a delicate specialised surgery that has poor success rate. Null Hypothesis: Person does not have the disease. Type 1 error: Person does not have the disease but recommended for surgery. (Rejected true Null Hypothesis) Type 2 error: Person has the disease but not recommended for surgery. (Accepted false Null Hypothesis) In this example, Type 2 error might cause the legitimate patient to not have the surgery which is bad, but it is much worse to have a person without the disease undergo the delicate critical surgery. The legitimate patient may re-do the tests, if he still feels the symptoms of the disease and may be re-diagnosed to undergo the surgery. In this case, a Type2 error or a Missed alert is preferable.

Takt Time Concept - Takt is a German word, It describes the conductors baton (for example in music orchestra). It is the concept that all activity within a business is synchronized by a rhythm, set by the customer demand. To simplify this concept, auto-industry, where mass production is done in ‘pull’ manner, has generally described it as “Time Available to Complete Task (Task here means production of one unit e.g a car). An organization may decide and make suitable arrangements to produce a unit (product/service) in Takt-time or slightly less than Takt-time, repetitively in a cyclic manner, this speed at which production is done to ensure org meets the customer requirement is called Cycle Time. And total production time from start to end is called Lead Time. To calculate the 'Takt time', following formula is used, Takt = 'Production Time Available' / 'Customer Demand'. 'Production time Available' is derived by deducting the Lunch and tea breaks, Team briefing times, TPM breaks, Clean down time, etc from 'total available time', as per industry practices. Hence 'Takt' is in fact the goal or target rate. Takt & 'Resource planning' is closely related - As demand may fluctuate, a takt time can be then calculated for anticipated demand (or known demand) to plan resource levels. This applies across the board for any production operation, as well as Lean operations. Why Takt is important & decisions it affects/drives- Takt Time regulates following, 1. The pulse of the Production System, and so the resources required ! 2. Rate of fulfillment of customer demand or Pace of sales !! 3. Links production activity to actual customer demand !!! 4. Ensures all production activity will be synchronized from 1st process to final assembly process, which is nothing but the balance flow. Takt time concept helps to set the flow of production. Work balancing is done to match to takt (by applying lean tools & practices) and so the flow of production is in tune with customer needs. Hence Takt is enabler for work balance in the business. Successful Takt planning drives the business decisions which are strategic as well as tactical in nature. Takt drives organization to meet the strategic objectives of business, for example - Customer Satisfaction, Profits, Investment decisions, ROI, ROCE, Payback, Market Share and Growth. Also effective takt planning drives org to meet operational level objectives (Tactical), for example - Effective use of its people and plants, inventories, cashflow, productivity and various costs. Whole SCM related decisions are driven by takt planning decisions. Calculations/Decisions on Takt eventually drives/affects the decision on Technology selection, Equipment selection decisions, Capital Investment, Operations cost, Offloading decisions / in-house production, Manpower & skills decisions, etc. Also, Identifying the areas of under-performance or waste in the system is the total focus of Lean and there Takt plays a vital role & becomes driver of improvement efforts. - Written by Vivek Dahake, based on experience in Auto-mfg-industry.