| SPID | summed pain intensity difference |
|---|---|
| TDI | temperature difference integration; three-dimensional interlocking [hip]; toluene 2,4-diisocyanate; ... |
| TID | time interval difference [imaging]; titrated initial dose |
| RMSSD | root mean square successive difference |
|---|---|
| SDNR | signal difference to noise ratio |
| SDD | smallest detectable difference |
| SDD | standard deviation of the difference |