“…The change‐point problem can be described by the following example: that is, we have a switching diffusion process with unknown threshold ϑ . Such models are called threshold diffusion processes like threshold autoregressive time series (Chan & Kutoyants, ), and statistical problems related to this model are singular (Kutoyants, ). If we have a cusp‐type singularity as where , then, for κ close to zero, we have cusp‐type switching similar to the change‐point case, but without jump.…”