Other factors are also important
When calculating a national average, the results must be adjusted to reflect other factors such as the type of garden.
There are many other factors aside from regional differences that will affect the mean counts. For example, some species are more likely to be found in rural gardens as opposed to urban gardens. The proportion of survey returns from rural areas has increased from 19% in 2007 to 27% in 2012. If we do not account for Garden Type, then species that are more common in rural gardens will show an apparent increase in abundance that is not due to any real change in their abundance.
When we apply an additional weighting for garden type (Figure 1) the results do not change much in this case. It appears as though tūī are not as affected by Garden Type as they are by Region
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