Joy Lian

A recent study by the School of Forestry and Environmental Studies has elucidated the most important factors affecting the value of second hand smartphones.

The researchers from Yale and the Coller School of Management at Tel Aviv University in Israel found that the intangible properties of a smartphone — namely the brand — had a bigger impact on delaying the depreciation of its value than reparability, which has previously been viewed as the primary factor in determining its lifespan. The study was published in the Journal of Industrial Ecology on Aug. 25.

“We ended up analyzing nearly 500,000 sales of used smartphones, and we found that while reparability and capacity had no more than a marginal impact, brand had a pretty substantial impact on value preservation,” said Tamar Makov FES ’19, the primary author of the study. “We found that Apple phones lose all their market value about a year after Samsung phones, even if they are technically equivalent.”

The researchers collected data from almost 500,000 listings of used Apple and Samsung smartphones on eBay in the first quarters of 2015 and 2016. They extracted detailed information about the devices, including reparability, capacity, screen size, condition, seller ranking and sale type. They then tested the relationship between these variables and the depreciation of a smartphone’s value.

From this model, they determined that the brand and age of a phone had a significantly greater effect on the phone’s value than reparability. The researchers then used this finding to predict value depreciation.

Tomer Fishman, co-author of the paper and a lecturer at the Interdisciplinary Center Herzliya in Israel, noted that this finding does not mean people should start buying Apple phones over other brands. Fishman worked on the study as a postdoctoral associate at the School of Forestry and Environmental Studies.

“If everyone starts buying only Apple phones, then the brand effect may change. For example, it may no longer be as powerful as it is a comparative thing,” Fishman said.

Makov noted that consumption is driven by both technical and behavioral factors — and consumers are not always rational actors.

Marian Chertow, a professor of industrial environmental management and co-author of the paper, said that much of the research in the area focuses on the technical, rather than the psychological, solutions to problems of sustainability.

“When you solve problems, you want to diagnose them, you want to study them, you want to research them. But if you don’t ask why are people are doing things that way, then you can’t get change,” Chertow said.

Even though a large sample size was used, there are still shortfalls involved in focusing on secondhand sales data, Makov noted. She said that one of the biggest limitations of the study is selection bias — one could argue that both the worst and the best phones do not end up getting sold on eBay.

Another limitation could be survival bias, Makov added.

“The older phones that we have are also probably the phones that are in better condition, so it might be that most phones do physically die after three or four years of age, but what turns out on eBay are only phones that survive,” she said.

According to Jon Powell ENG ’18, a researcher with Yale’s Environmental Performance Index and the CEO of both PTP Informatics and Waste University, further research could examine the question over a longer period. With this longer period, researchers could assess whether brand effects on product reuse fluctuate with changing consumer preferences.

Makov said that future research could take a deeper look into perceived versus functional obsolescence. Also, she said that more behavioral experiments could be done to test if people’s expectations of the quality of a phone actually affects its perceived functionality.

Makov noted that she is already working on another study that looks at the usage of benchmarking applications — through which users can check the functionality of their phones. Makov wants to see if people use these applications when their phones are not working or when manufacturers announce a new product.

In 2017, Apple and Samsung together commanded roughly 70 percent of the U.S. smartphone market.

Darryl Laiu | darryl.laiu@yale.edu .