Pupil Home - School Distance
The starting point of our spatial analysis is to calculate the straight-line (“as the crow flies”) distance between the centre of a pupils home postcode area and the actual school they attend. In the STHC Output this is called the “Pupil Home – 'Actual' School Distance” or just "'Actual' Distance" for short. This represents the length of a single pupil journey from either home to school or back again, by the mode of travel recorded in the school census.
We also determine the nearest school that a pupil could attend given their national curriculum year (NCY), and measure the distance to that too. This is called the “Pupil Home – 'Nearest' School Distance” or just "'Nearest' Distance" in the output. Arguably this represents the "ideal world" scenario from a sustainable travel point of view - all pupils attending their nearest school. On a practical level as far as our analysis is concerned however, it gives us something to put the actual distances travelled by pupils into context. It puts a number to the reduction in overall "child miles" that is theoretically possible through "sustainable travel" measures alone given the current geographic distribution of schools and pupils (i.e. trying to change the travel choices made by the pupils rather than changing where they or the schools are). In other words it gives a quantifiable, and therefore directly comparable, measure of the current distribution of schools with respect to the pupils (or vice versa)!
So why do we use the straight-line distance rather than the distance of the route actually travelled? Well for start we don't actually know the route that the pupil will take to school. Yes you could make a good guess for those coming by car as they are driving along the roads, but are they coming by the "quickest" route or the "shortest" route? And what happens if they "park and stride", ie. park at a designated car park near the school and walk the rest of the way? And what about those that car share and so may not take the direct route to the school? As for those coming by bus, how far do they actually travel along the road? And what about those that may not be using the road at all? Walking and cycling paths are often not part of a road network, in which case we do not have the basic data that will enable us plot the route and therefore measure the distances involved. No it is much better to keep the spatial analysis process as simple and transparent as possible and make it consistent irrespective of the mode of travel involved, that way we can always be sure of comparing "apples with apples". Further, more complex analysis can always be undertaken using the GIS data included in the STHC Output if clients are so minded.
Note: In the STHC Output - in particular the Distance Stats spreadsheets and also the STHC School Report - we report both the minimum and the maximum "Pupil Home - 'Actual' School Distances" calculated. Unfeasibly long journeys for walking and cycling more than likely indicate miscoding of the original school census data - either the pupil postcode and/or the mode of travel - rather than super human pupils! Looking on the positive side, such errors would not have come to light unless spatial analysis had been undertaken so it is a necessary step to improving data quality for the future. We therefore simply encourage schools in this situation to try and ensure that any errors are corrected in time for the next school census.
Very occasionally a minimum "Pupil Home - School Distance" of zero is reported. This is an unavoidable consequence of using the centre of the postcode unit for the pupil location rather than the pupils actual home address. If a school does not have it's own unique postcode - and many smaller primary schools don't - it will be shared with adjacent houses. Thus any pupils attending the school from those houses will be shown as having a travelling distance of zero!