38. The study reported in Gait Patterns During Free Choice Ladder Ascents (Hum. Movement Sci., 1983: 187—195) was motivated by publicity concerning the increased accident rate for individuals climbing ladders. A number of different gait patterns were used by subjects climbing a portable straight ladder according to speci ed instructions.

The ascent times for seven subjects who used a lateral gait and six subjects who used a four-beat diagonal gait are given.

Lateral .86 1.31 1.64 1.51 1.53 1.39 1.09 Diagonal 1.27 1.82 1.66 .85 1.45 1.24

a. Carry out a test using a  .05 to see whether the data suggests any difference in the true average ascent times for the two gaits.

b. Compute a 95% CI for the difference between the true average gait times.