The three experiments were conducted by a total of 1,005 pupils in the UK (694 in primary schools, 311 in secondary schools)

Experiment 1: Does buttered toast tend to land butter-down ?

To find out if this 12 per cent difference is statistically significant, we can calculate its "p-value" - that is, the chances of getting at least as big a difference as that observed just by fluke. This probability turns out to be extremely low (p ~ 10-127) Thus the 62 per cent rate is both substantially, and statistically significantly, different from the rate expected by chance alone.

Experiment 2: Is butter the cause ?

Results

Again, statistical significance tests against the null hypothesis of a 50:50 split gives an extremely low p-value (~ 10-57). Toast with just a "B" on it thus still lands face-down at a rate substantially, and statistically significantly, different from value expected by chance alone.

Experiment 3: Is height the cause ?

Results

Statistical analysis

Both these differences are statistically significant (p = 0.003 and 10-37 respectively).

So increasing drop height to 2.5 metres gives a substantially and statistically significantly higher probability of producing a butter-up landing.

Conclusions

1. Toast really does have a tendency to land butter-side down.
2. The presence of butter is not the major cause of butter-side down landings.
3. The principal cause is height: toast falling from waist-height does not have enough time to come butter-side up again.

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