The results have been presented in various studies by the
authors (Yoxall et al., 2006, 2010a), and showed that for males and
females there was a significant drop in strength with age, and that
by 70 years of age, statistically 50% of women would not be able to
access 50% of the jars they bought. Similarly the results showed that
15% of women of any age would struggle with 50% of the jars they
bought; indicating that openability of jars of this type is a significant
problem.
The authors have also attempted to study ease of access using
analytical techniques (Yoxall and Janson, 2008). Simple mathematics
showed that the limiting torque that a consumer can apply
to open a container is governed by Eq. (1).