A shmoo plot shows the result of testing something while changing two variables. This is used in semiconductor manufacturing to test wafers. This concept could be used to help make retirement decisions. Example Shmoo plot images

One example is deciding on when a couple should take social security. We would first pick the variable we want to see the effect of, and then the two variables to adjust. In this case, we could choose net assets at end of plan and then claiming social security age for each person as the x and y variables. Projection Lab would then vary the claiming age for each person and produce a plot showing the net assets for each combination.

This would really help in try to make some decisions like: 1) how much to save in 401k vs Roth (dollars saved in 401k vs dollars saved in Roth) 2) When to stop saving in 401k (date vs dollars saved in 401k) 3) Check for holes in longevity risk for a couple (longevity age of each person in a couple) 4) Check for maximum spending (date vs dollars spent in retirement)

Income lab has something similar for their social security planning, but having the ability to pick any three variables would be amazing.

It would also be nice if these plots could be saved and presented as a collage. Then you might be able to see the effects across multiple variable sets in a single glance.

Somehow being able to solve for more that 3 variables would be great, but I can’t think of how to show it visually.

I think Compare Mode should let you do these kinds of comparisons today. Have you tried that?

The shmoo plot would give you a visualizations of multiple comparisons that could hopefully give some insights. For example, I created the shmoo plot below looking at the ending balance for liquid assets at plan end and varied the life expectancy, where my age is on the left, my spouse’s age is on the bottom:

90 | 1459 1599 1862 2171 2456 2640 2800 85 | 1351 1484 1742 2021 2280 2431 2400 80 | 1215 1326 1545 1805 2004 2016 2000 75 | 1108 1195 1376 1597 1604 1485 1400 70 | 1103 1177 1333 1180 1080 838 644 65 | 1031 1098 895 650 428 39 -147 60 | 1009 723 457 111 -83 -12 -11 ------+--------------------------------------------------------------------------------------- 60 65 70 75 80 85 90

So there is an interesting pattern. Why is it that my spouse has a worse outcome if I die early than if my spouse dies early. I would not have seen this pattern if I did not actively look for it as part of the suggestion.

At this moment I have been unable to determine the exact cause of this pattern. I did find an extra $200k withdraw at at 60 in one plan and not the other. So I still need to investigate.

Without going through this exercise I would not have found this issue, and it took me a good 20 min to build the above table.

I just wonder if there are other possible issues hiding in my plan that I just do not know about.

Table in code block:

+------+------+------+------+------+------+------+------+
| 90   | 1459 | 1599 | 1862 | 2171 | 2456 | 2640 | 2800 |
+======+======+======+======+======+======+======+======+
| 85   | 1351 | 1484 | 1742 | 2021 | 2280 | 2431 | 2400 |
+------+------+------+------+------+------+------+------+
| 80   | 1215 | 1326 | 1545 | 1805 | 2004 | 2016 | 2000 |
+------+------+------+------+------+------+------+------+
| 75   | 1108 | 1195 | 1376 | 1597 | 1604 | 1485 | 1400 |
+------+------+------+------+------+------+------+------+
| 70   | 1103 | 1177 | 1333 | 1180 | 1080 |  838 |  644 |
+------+------+------+------+------+------+------+------+
| 65   | 1031 | 1098 |  895 |  650 |  428 |   39 | -147 |
+------+------+------+------+------+------+------+------+
| 60   | 1009 | 723  |  457 |  111 |  -83 |  -12 |  -11 |
+------+------+------+------+------+------+------+------+
|      |  60  |  65  |  70  |   75 |  80  |  85  |   90 |
+------+------+------+------+------+------+------+------+