Hypothesis: New items become less profitable over time.
Source Data: I picked the Noctis because I have data for 188 sales ranging from Dec/2010 to June/2012. I wanted to look at the Tier3 Battlecruisers, but I lack enough trades on these to be statistically meaningful.
The slope of the trendline suggests that the profitability is every so slightly going down. I assumed that the decline would be much greater than shown by the trendline.
Since a recently added item didn’t show a downward trend, I extend the research sampling. I picked a common item, a common ship, and a high volume item.
1. Here is the graph for 1,534 Damage Control II’s. It shows more downward profitability than the Noctis.
2. The Ishtar is a very popular ship for ratting and mission running. 112 Ishtar trades show a greater profitability decline than the Noctis.
3. The trend of 572 Cybernetic Basic implants shows a slight decline.
Conclusion: I could not prove my hypothesis with data from Noctis sales and I’m showing greater profit decline on more common items. I’ll revisit this when I have more data for the Tier3 Battlecruisers and the modules introduced in Inferno.