Mean of grouped data: step-deviation method (Assumed mean A, class width h, coded deviations u_i)

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Assumed mean A, class width h, coded deviations u_i

What each symbol means

SymbolWhat it stands for
hUniform class width
u_iInteger step from A
x_iMidpoint of i-th class

When to use this

Equal class widths; midpoints x_i; any convenient A (often mid class).