I have a strong personal interest in Parkinson’s disease and the way in which it affects people’s lives. It is an area I intend to work in once qualified.

There have not been many well-controlled experiments where auditory and visual cueing to improve gait speed have been compared and this was seen as a gap.

Parkinson’s disease affects 1 in 55 people which makes it an important research area in terms of being able to make a positive difference to a large percentage of the population.

As the research question leads to a deductive inquiry process, a quantitative approach has been decided on. A quantitative study will allow an examination of the relationship between the dependent variable (gait speed) and the independent variables (auditory cueing and visual cueing).

It is rational to use a true-experimental design, in particular a multi-site randomised cross-over trial, with measurements of gait speed made before the first and after the last cueing intervention. This choice of design does not leave room for difference in interpretation of results, it simply measures what is, and will provide the necessary data for the intended research.

Gallin and Ogniben (2007) have suggested that if all parts of the study are valid and reliable, 100-200 participants in a randomised controlled trial can have statistically significant findings. Based on this, participants will be volunteers recommended by consultants and/or physiotherapists from a number of hospitals around New Zealand and the Parkinsonism Society of New Zealand, with the aim of 100 people to be included in the experiment.

To be included in the study, subjects will be required to have PD, have slower gait speed since developing PD, have no cognitive difficulties and be able to walk for at least twenty metres over flat ground ten times with rest breaks. They will be required to be off medication for the duration of the testing and not be currently receiving any physiotherapy. All subjects will need to have normal or corrected-to-normal hearing and vision, no cardiovascular limitations impairing walking ability/efficiency and no other limitations affecting gait. Subjects will need to be between the age of 20-80 years and in the Hohen and Yahr stage 1-4 (Hoehn & Yahr, 1967; Lewis, Byblow & Walt, 2000). If they all meet the selection criteria, each of the participants will be as closely sex, age and height-matched as possible to eliminate these as confounding variables and then randomly allocated to one of the two cueing groups (which will be crossed over after a three week period).

The instrument used as an auditory cueing device will be a metronome beating 25% faster than the subject's fastest gait speed. They will be encouraged to listen to the metronome and try to match their heel strike with the beat along a twenty metre walkway. The visual cueing instrument will be a series of brightly coloured parallel lines placed along a twenty metre walkway at intervals equal to 40% of a subject's height. They will be instructed to try and step on each line with each step. Both interventions will be performed ten times, with rests in between. The choice of these instruments is justified by the fact that they were used in a previous study and both showed a marked improvement in gait speed as well as showing high test-retest reliability, ensuring rigour (Suteerawattananon et al., 2004). In the same study gait speed was measured with a digital stopwatch and expressed in centimetres per second which will also be used in this experiment. The outcome measure used to determine gait speed will be the ten metre walk test (10MWT). Subjects will be asked to walk along the twenty metre walkway at their fastest speed, with the middle ten metres being measured to reduce acceleration and deceleration effects. The 10MWT has been found to be valid and reliable in measuring speed in people with PD and will be used as a measure of gait speed for baseline (pre-test) and post-test stages (Ledger, Galvin, Lynch & Stokes, 2008).

Of the ten times each intervention is measured, all will be recorded in a standardised logbook at each site by the tester and a mean value will be determined.

Internal validity will be protected by means of the standardised training which each tester will receive to ensure that procedures are the same at each testing site. If all procedures are the same in each centre and the sample size is not significantly lessened due to drop outs, this will also provide external validity.

A possible limitation of this study is that because it is not rational to blind the participants or the testers (as the cueing interventions are so dissimilar), a placebo effect may occur when each group crosses over.

From the mean values recorded in the logbooks, two sets of inferential bivariate analysis will be conducted to determine the relationships between auditory cueing and gait speed and visual cueing and gait speed.

The auditory cueing results from both group A and B will be mixed and the same for visual cueing. For each set, a scatter gram will be drawn illustrating the relationship between the intervention and the mean values of gait speed for each individual. From each scatter gram a mean measure of both initial and final gait speed will be determined.

A test for statistical significance between the two will be tested using the appropriate statistical significance program. It is from these measures that the mean improvement in gait speed will be obtained and the research question will be answered.

To ensure that the findings are statistically significant, the mean improvement in gait speed needs to have occurred in at least 95% of the participants (Hopkins, 2002).

If it is found that one of the cueing interventions has a significantly more beneficial effect on gait speed than the other, it could then be confidently used by clinicians as the best method of the two when aiming to improve gait speed in patients with Parkinson’s disease.