Based on various parameters, Cliff Arnall, a British psychologist has developed a new formula that could help in calculating the play value of a toy.

The formula is – P(i)+P(o)+Cr + S + U + H + (T*L) / (square root of C)=play value.

In the formula, parameter P(i) stands for playing alone; P(o) for playing with others; Cr for creativity of the toy; S for co-operative social interaction with others and U for utility of the toy; H denotes whether it can be handed down to other child; T for estimated time played in a week; L for the toy’s longevity and C for the cost of the toy.

A toy that scores 40 or more is considered to be of excellent value, as per the equation.