First pass yield is defined as:
(number of units that successfully pass through a process)
(number of units that entered that process)
It can be calculated for multiple time periods- daily, weekly, monthly etc. This is one of the most common metrics for measuring the quality of a process.
This short guide will help you decide how to calculate first pass yield in your app. There are multiple ways to calculate this metric within Tulip, and this guide will provide one example.
Before using this guide, you should be familiar with the concept of "app completions".
Structuring Your App
Before we look at the Analytics Builder, we should examine the data being tracked in the app itself.
Let's imagine that your app has a "Defect Report" button on every step. Like this:
And the defect report form looks like this:
In the example above, a part requires rework if the answer to the question "Is the defect repairable?" is yes. If no, it should be scrapped.
When the operator presses "Submit" on this step, you should update a variable called "defect_type" to indicate if the part was "scrap" or "rework".
Here's what that trigger action looks like:
Next, you must decide whether an "app completion" should be triggered when an operator presses the "Submit" button after reporting rework or scrap.
This depends on your process. If the operator should immediately begin rework when they log an issue, then the app should NOT be completed. But, if the part must be sent to another department or fixed independently, then an app completion should likely be registered.
In most cases, if the part is scrapped, an app completion should be registered.
Regardless, the formula should look like this for first pass yield:
(number of app completions where the part is NOT scrap OR rework)
(total number of app completions)
Here's how to create that analysis.
Creating the First Pass Yield Analysis
After you have set up the variables in the app, you can create a new Number analysis in the Analytics Builder.
In the app of your choice, click the "Analytics" tab on the App Summary View, then choose "New Analysis".
Then, choose the "Single Number" analysis for the list of templates.
After that, you will see a list of 4 fields in the Context Pane on the left side of the screen:
We will just focus on the "Number" field. We need to create a fraction here. Select the "Number" field, and choose "Change" next to the Y Axis.
Choose "Aggregation Functions", then "Percent Where True" from the list.
Now, we need to see the percentage of completions where the variable "defect_type" is blank, since it would only have a value when scrap or rework is logged before the operator presses the "Complete" button.
Click the words "Select a variable or function" and choose "App variables" then the "defect_type" variable.
Finally, click the orange "Equals" text and choose "Is Blank" to find all app completions where this variable was blank.
The resulting percentage should be your first pass yield for this part of the process.