APPENDIX
THE STATISTICAL SIGNIFICANCE OF A TREND
The statistical significance of a trend depends on
the closeness of the data-points to a straight line. In the example
below, the computed upward trend (the "m" in the regression
equation) for Mathematical Science is marginally greater than
that for Engineering & Technology. However, the greater amount
of zigzag in the data-points making up the former means that the
upward trend is less robust, statistically, than that of the latter.
Of course, the trend relates only to the data-points displayed:
there is no way of telling from the data where the next data-point
in each sequence might lie. Observers of once-booming house prices
and stock markets will be only too aware of the force behind the
financial services' warning that past performance is no guarantee
of future success.
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