In a science experiment, we can remove all other factors and isolate ONE change. Oh look, it was the extra Oxygen that made the fire brighter. We know this because NOTHING else was changed.

In education, we do not work in test tubes. Applying cold scientific methodology to Social Science is recognised as flawed to the extent that it has its own pejorative name: scientism. 

Children are exposed to a range of known and unknown factors that cannot and should not be scientifically controlled: We would not want to exclude every supportive factor from a child to identify the specific impact of just one. 

This must be remembered when considering data measures in a school - for the good of the children the data is supposed to be supporting.

INSTEAD, it is clear that when we consider IMPACT and MEASURE it is like considering the IMPACT of a pebble on a pond and considering the MEASURE by looking at the size, intensity etc. of the RIPPLES. 

BUT, there is never only one pebble ever being dropped - Imagine a pond with hundreds of pebbles being dropped at the same time. How are we to know which of the isolated pebbles caused or increased any specific ripple. How are we to know that it wasn't a COMBINATION of supportive factors that, in that specific context, positively impacted on creating that large impact? Or even a small negative factor lost in a larger positive factor - ripples hitting each other.

The clear truth appears, we are not to know. 

Education is not an exact science. We do out best to identity better approaches and systems (a range of factors) but we can never be sure that 'THIS' is the RIGHT method. 

No such deduction is justified. 

Instead, we, at best, may identify the best ways of encouraging renewed and continuing research, exploration and consideration within this ever changing reality.

The dangers in failing to understand and apply this understanding to actions is clear:

"The more any quantities social indicator is used for social-decision making, the more subject it will be to corruption pressures and the more apt it will be to distort and corrupt the social processes it is intended to monitor." Or simply put, "When test scores becomes the goal of the teaching process, they both lose their value as indicators of educational status and distort the educational process in undesirable ways." Cambell's Law https://en.wikipedia.org/wiki/Campbell%27s_law 

Rules: Consider the multivariate factors (PEBBLES) impacting on the intended outcome.

Rules: Consider a range of data systems AND wider details and uncertainties.

Rules: Take Data with a PILE of salt.