38 Questions
What is the purpose of determining the desired confidence level in work sampling?
To determine the sample size required
In Example 3, what is the estimated value of sample proportion?
0.35
What is the acceptable error level in percent in Example 2?
5%
What is the purpose of work sampling in the context of time standards?
To determine the percentage of idle and working time, as well as the average performance index
What is the formula to calculate the sample proportion?
Idle observations / Total observations
What is the desired accuracy in Example 4?
3.5%
What is the purpose of determining the desired accuracy in work sampling?
To ensure the results are accurate within a certain percentage
In Example 4, how many minutes is the drill-press operator idle?
72 minutes
What does the algebraic midpoint of a specific production batch or lot represent?
The incremental unit time or cost of the lot midpoint unit
What is used to calculate the unit cost of any particular or specific quantity or unit?
The cumulative number of units produced
What is the purpose of calculating the lot's midpoint?
To determine the unit cost of the midpoint unit
What is the relationship between the lot cost and the midpoint unit cost?
The lot cost is determined by multiplying the midpoint unit cost by the number of units in the lot
What is the variable that represents the number of units in the lot?
L
What is the formula for calculating the unit cost of any particular or specific quantity or unit?
Y = incremental unit time or cost of the lot midpoint unit
What is the variable that represents the incremental unit time or cost of the lot midpoint unit?
Y
What is the purpose of Crawford's Model?
To calculate the unit cost of a production batch
What is the primary purpose of setup elements in production?
To change over from one batch to the next
Which of the following is a characteristic of machine-controlled elements?
They have little or no random variation
What is the formula for computing the batch time?
Tb = Tsu + Q Tc
What is the purpose of the production elements in production?
To process work units within a batch
What is the difference between operator-paced and machine-controlled elements?
Operator-paced elements are dependent on worker pace, while machine-controlled elements are dependent on machine operating parameters
What is the result of an increase in the quantity of work units (Q) on the batch time?
The batch time will increase
What is the primary purpose of work measurement in certain circumstances?
To measure a manual task and establish a time standard
What is the percentage of idle time in the example given?
10%
What is the total minutes worked in a shift of 8 hours?
432 minutes
What is the significance of the normal distribution curve in work sampling?
It graphically depicts the probability of certain chance events occurring
What is the most common level of confidence in work sampling results?
95 percent confidence
What is the primary reason for determining the level of confidence in work sampling results?
To determine the level of significance in the results
What is the significance of the 95 percent confidence level?
It is a moderately high level of confidence
What is the purpose of calculating the sample size in work sampling?
To determine the total number of observations required for an investigation
What percentage of the time will random observations reflect the facts?
95% of the time
What is the formula for the 95% confidence level?
1.96 σp
What is the confidence level represented by 2 σ limits?
68%
What is the percentage of the area under the curve for a 99% confidence level?
99.9%
What is the formula for the 99% confidence level?
2.58 σp
What is the confidence level represented by 1 σ limits?
68%
What does the 95% confidence level indicate?
The findings are likely to reflect the truth in 95 out of 100 cases.
What is the formula for the 99.9% confidence level?
3.3 σp
Study Notes
Production Elements
- Production elements are associated with the processing of work units within a given batch and are performed once per work unit.
- There are two types of production elements: operator-paced elements (manual) and machine-controlled elements (machine time depends on machine operating parameters).
Batch Time
- Batch time (Tb) is the sum of setup time (Tsu) and cycle time (Tc) multiplied by the quantity (Q): Tb = Tsu + Q Tc.
- Example: Compute the batch time of a production with a cycle time of 5 minutes, an output of 35 units, and a setup time of 3 minutes.
Work Measurement
- Work measurement is used to measure a manual task, establish a time standard for an operation, and determine a performance index or performance level for a worker during their working time.
- Example: Calculate the idle time percentage of a worker who is idle for 5 minutes out of 50 minutes, and works for 90% or 432 minutes in an 8-hour shift.
Normal Distribution Curve
- The normal distribution curve is a frequency distribution that graphically depicts the probability of certain chance events occurring.
- Confidence levels: 95% (1.96 σp), 99% (2.58 σp), and 99.9% (3.3 σp) represent the area under the curve.
Determining Sample Size
- The sample size required for a study can be calculated based on the desired confidence level and acceptable error level in percent.
- Example: Calculate the sample size required to find the number of observations with a desired confidence level of 95% and an acceptable error level of 5%.
Time Standards
- Time standards can be determined using work sampling, which involves measuring the percentage of idle time and working time of an individual.
- Example: Determine the time standards for a drill-press operator who is idle for 15% of the day and works for 85% of the day.
Learning Curve
- The learning curve is a model that describes the relationship between the production time and the number of units produced.
- Example: Calculate the unit cost of a batch using Crawford's model with an 80% learning curve.
This quiz covers the different elements involved in production, including setup elements and operator-paced elements. Learn about the activities required to change over from one batch to the next and the processing of work units within a given batch.
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