Does Size Matter: A Single Case Experimental Design of Limiting the Depth of Penetration During Intercourse

The investigators will conduct a single case experimental design (SCED), in which a woman acts as her own control with a reversal design between randomly allocated phases. These include a control phase (A) and phases with various sizes of penile rings (B, C, and D).

The male participant will be asked to measure the length and girth of their erect penis using standardized instructions and flexible tape measure before the start of the experiment. This will partly determine the inner circumference of the ring provided. The male participant will be given instructions on how to use the penile rings and ensure that the female participant is blind to the size of the ring used.

There will be randomization (a) to the phase (the size of ring) and (b) the number of times of intercourse within a phase. The male partner will be blind to ratings made by the female partner. There is no carry over effect from one phase to another. The randomization of the phase means less guessing of the size of the ring, and less interaction with moderators (e.g. menstrual cycle, alcohol, holiday or life events randomly spread across phases). In a SCED, one then replicates in Case 2, Case 3 etc and a meta-analysis is conducted of all the single cases.

Randomisation will occur to either

1. Phase A "Normal" intercourse with very thin (less than 0.5cm) ring randomised to either 3, 4 or 5 episodes of intercourse)
2. Phase B - 1" ring randomised to either 3, 4, or 5 episodes of intercourse)
3. Phase C - 1.5" ring randomised to either 3, 4, or 5 episodes of intercourse)
4. Phase D - 2" ring randomised to either 3, 4, or 5 episodes of intercourse) The male partner will be kept informed by text or email or phone (whichever is convenient) of when to change the size of ring and the number of times it should be used. The female partner will be asked to be blind to the size of ring used after each episode of intercourse. Blindness will be tested by asking if the female partner "saw" the size of the ring or whether she was able to guess when a change in the size of the ring occurred.