Since posting my last blog entry on how I loosely used multi-objective decision analysis to guide my decision to purchase a new washing machine, I have been accused of giving “more thought to [my] washing machine purchase than Congress gave to [the] budget.” This blog post is certainly not going to disprove that claim.

My husband and I based our purchase on prices, quality, and functionality. In this post, I will confess that our analysis was somewhat wrong. I thought that I knew what a new washing machine would be like. This was a reasonable assumption, since after all, I’ve been using washing machines for years.

Once I started to use the new washing machine, it became clear that

loads take longer to complete (sometimes much longer to get clothes clean). laundry is less wet when it comes out of the washing machine.

The combination of these two points means that my dryer is no longer the bottleneck, it’s the washer. It also takes away some of the benefits of drying laundry outside. Air drying used to be a huge time saver for me in the summer. Not so any more. This is a good thing, because with a baby at home and tenure looming, I have less energy and more laundry to do. I use my dryer more frequently this year. I no longer schedule my laundry around the dryer time, which has the side benefit of giving me a little more flexibility. The longer wash cycles are a pain, but the “Tumble Fresh” option keeps the laundry smelling fresh if I let it sit in the washer for a long time.

My time spent doing laundry is determined by the washing machine and its capacity. The large capacity of our new washer helps me to avoid splitting some loads of laundry into two loads, which would be necessary at a smaller capacity. A larger capacity wouldn’t necessarily save me any loads, because all of my “full loads” fit into our new washer. This will certainly change when my kids get bigger and wear bigger clothes, and I may kick myself for not buying the biggest capacity available.

All of this suggests replacing my “capacity” criteria with a “throughput” criteria, where the throughput can be evaluated by considering the total time spent “doing” laundry per week based on the total number of loads:

Total time = (Number of loads) x max{Washing Time, Drying Time}

Then, the mid-level washer becomes the overwhelming favorite, even when performing a sensitivity analysis on the weight for throughput (see below). Although this improvement is a step in the right direction, I remain skeptical of its usefulness. Would I have come up with a spreadsheet to justify buying a high-level washer had we bought the priciest washer? I’ll have to leave that one a mystery and get back to work.

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