Help Manual

Contents






Sigma Magic Help Version 17

Time Study

Overview

The time study tool can be used to perform a time study analysis. The inputs to the time study are the individual times for each step in the process. The outputs of the time study are the expected total time for the entire process set and the confidence interval calculated at the given confidence level. Time study can be used anytime you need to determine the time each step in the process takes. These studies are usually conducted to develop work standards. In a Lean process, time is an essential element, and time studies can help capture the amount of time each step in the process takes so that they can be used to set the standard and then continuously improve the standard over time. The cycle time for each step in the process can also be compared to the TAKT time to determine if a process has any bottlenecks.

To add this tool to your workbook, click on Lean and then select Time Study.

Inputs

Click on Analysis Setup to open the menu options for this tool.

Setup

A sample screenshot of the setup menu is shown below.
Time Study
1
Analysis Type: Specify the tool format for this analysis. This selection is not enabled since there is only one format available.
2
Num Rows: Specify the number of rows of data you would like to enter on the worksheet. This information is used to format the worksheet. Note that any data below this formatted area will be cleared.
3
Num Observations: Enter the number of repeat observations for each step. Repeat observations help you capture the variation you have in your process. Try to measure each step at least three times.
4
Time Calculation: Specify how you want to calculate the total process time. The different options are:
OptionDescription
AverageUse the average value for the overall time.
MedianUse the median value (a good option if you have outliers in your data).
Average (excluding min/max)Use the average value, which is calculated after eliminating the lowest and highest values.
CI BoundsUse the 95% confidence interval (lower or upper bound)
MinimumUse the minimum value (if you want to set aggressive targets)
MaximumUse the maximum value (if you want to set a conservative target)
5
View Example: Click on this button to open the example file. You can view the example to get an idea of how to fill out this tool, or you can use the example as a starting point and modify it to meet your project needs.
6
Help Button: Click on this button to open the help file on this topic.
7
Cancel Button: Click on this button to exit without saving any changes.
8
Create Design: If this is your first time using this template, click this button to format the worksheet template. You can also update the worksheet format any time, but remember that you may lose any data entered on this worksheet. Once you are happy with the worksheet template layout, you must enter any required data on the worksheet. When the data entered into the worksheet is complete, you can click on Analysis Setup and then Compute Outputs to generate analysis results.
9
Analyze Design: Click on this button to save all changes and compute the outputs for this analysis. Review the results of your analysis and make changes to your inputs if required to update analysis results.
A sample screenshot of the worksheet is shown below.
outputs In the worksheet, enter the details of your process.
NumDescription
1 Enter the number of the process step (or just an index)
2Next, enter the description for each step in the process.
3For each step in the process, enter the observed time. The units are not specified so that you can enter any units (minutes, hours, seconds, etc.), but make sure you are consistent in your data entry. If one value is entered in minutes, all values should be entered in minutes.

Charts

You will see the following dialog box if you click the Charts button. Charts
1
Title: The system will automatically pick a title for your chart. However, if you want to override that with your title, you can specify a title for your chart here. Note that this input is optional.
2
Sub Title: The system will automatically pick a subtitle for your chart. However, if you want to override that with your subtitle, specify a subtitle for your chart here. Note that this input is optional.
3
X Label: The system will automatically pick a label for the x-axis. However, if you would like to override that with your label for the x-axis, you can specify a different label here. Note that this input is optional.
4
Y Label: The system will automatically pick a label for the y-axis. However, if you would like to override that with your label for the y-axis, you can specify a different label here. Note that this input is optional.
5
X Axis: The system will automatically pick a scale for the x-axis. However, if you would like to override that with your values for the x-axis, you can specify them here. The format for this input is to determine the minimum, increment, and maximum values separated by a semi-colon. For example, if you specify 10;20, the minimum x-axis scale is set at 10, and the maximum x-axis scale is set at 20. If you specify 10;2;20, the x-axis increment is set at 2. Note that this input is currently disabled, and you cannot change this setting.
6
Y Axis: The system will automatically pick a scale for the y-axis. However, if you would like to override that with your values for the y-axis, you can specify them here. The format for this input is to determine the minimum, increment, and maximum values separated by a semi-colon. For example, if you specify 10;20, the minimum y-axis scale is set at 10, and the maximum y-axis is set at 20. If you specify 10;2;20, then, in addition to minimum and maximum values, the y-axis increment is set at 2. Note that this input is optional.
7
Horizontal Lines: You can specify the values here if you want to add a few extra horizontal reference lines on top of your chart. The format for this input is numeric values separated by semi-colon. For example, if you specify 12;15, two horizontal lines are plotted at Y = 12 and Y = 15, respectively. Note that this input is optional.
8
Vertical Lines: You can specify the values here if you want to add a few extra vertical reference lines on top of your chart. The format for this input is numeric values separated by semi-colon. For example, if you specify 2;5, two vertical lines are plotted at X = 2 and X = 5, respectively. Note that this input is optional.

Verify

If you click the Verify button, the software will perform some checks on the data you entered. A sample screenshot of the dialog box is shown in the figure below. Verify The software checks if you have correctly specified the input options and entered the required data on the worksheet. The results of the analysis checks are listed on the right. If the checks are passed, they are shown as green checkmarks. If the verification checks fail, they are shown as a red cross. If the verification checks result in a warning, they are shown in the orange exclamation mark, and finally, any checks that are required to be performed by the user are shown as blue info icons.
1
Item: The left-hand side shows the major tabs and the items checked within each section
2
Status: The right-hand side shows the status of the checks.
3
Overall Status: The overall status of all the checks for the given analysis is shown here. The overall status check shows a green thumps-up sign if everything is okay and a red thumps-down sign if any checks have not passed. Note that you cannot proceed with generating analysis results for some analyses if the overall status is not okay.

Outputs

Click on Compute Outputs to update the output calculations. A sample screenshot of the worksheet is shown below.
outputs The total time for all process steps is shown in the figure. The Excel table also shows the cycle time value for each step, depending on your selected methodology. The figure plots this data in a bar chart and then plots the confidence intervals for each step as whiskers. If you work with the average value, then it is expected that half the time, your times would be greater than the average and half the time less than the average. To pick a conservative time, use the maximum or minimum value from the confidence interval rather than the average value. If the analysis is completed without errors, the following message is displayed when you click the Compute Outputs button. outputs 2

Notes

Here are a few notes regarding this analysis:
  • To handle missing observations, you can leave the fields blank if you don't have the values. Note that you need at least two values to calculate the standard deviation. If you have less than two observations, the standard deviation is set at 0.0.
  • You can choose the default confidence level of 95%. This means you are 95% sure your total process time will be less than this value. You will be wrong only 5% of the time. As opposed to being wrong half the time if you work with the average value.
  • Currently, you can have up to 10 observations per step for this software version.
  • Note that the value you specify under options is only used when you create a new worksheet. After that, if you specify or override the value in the Time-Study worksheet, the software assumes that you want to use this new value for this spreadsheet.

Examples

The following examples are in the software's Examples folder.
  • Data was collected for one zone of assembly of TVs. Use the data in the reference file to do a time study at a 95% confidence level (Time Study 1.xlsx).



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