DTM.6:5.2 - Compatible partners can make an unfamiliar method worth adopting

Suppose the proposed method gives a group a benefit of 2 units over a fixed horizon and costs 0.5 to adopt. Exchange with a partner using the old method remains possible through manual conversion. The switching group bears conversion cost 3 per unit share of old-method partners.

If f is the share of its relevant partners already using the proposed method, its gain relative to continuing is:

g(f) = 2 − 0.5 − 3(1−f).

An independent estimate that omits partner conversion gives 2−0.5=1.5. The coupled estimate instead gives −0.9 at f=0.2 and 0.9 at f=0.8. At the lower share, ignoring compatibility therefore reverses the sign of the choice. Here other adopters facilitate adoption by reducing conversion work. No shared defensive response is needed.

An available adapter costing 0.4 over the same horizon and reducing the conversion coefficient to 0.2 changes the gain to 2−0.5−0.4−0.2(1−f), or 0.94 at f=0.2. The participants, cost allocation and horizon are unchanged. If costs instead shift to old-method partners, both parties’ consequences must be recomputed.

A comparison that records conversion work and partner composition can distinguish this account from an unrelated reluctance to adopt. Adoption still requires opportunity, capability and authority; a positive gain is not a transmission event. DTM.2/.4 supply those further questions.