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• Variable quantitativa mesurada<br />

en escala ordinal<br />

1r. Plantejament de les hipòtesis<br />

estadístiques:<br />

H 0 : Md 1 = Md 2<br />

H 1 : Md 1 ≠ Md 2<br />

H 0 : Md 1 ≤ Md 2<br />

H 1 : Md 1 > Md 2<br />

H 0 : Md 1 ≥ Md 2<br />

H 1 : Md 1 < Md 2<br />

2n. Fixar α<br />

Bilateral<br />

Unilateral<br />

dreta<br />

Unilateral<br />

esquerra<br />

3r. Càlcul estadístic de contrast: T<br />

= ΣR i<br />

R i: ordres de signe més freqüent<br />

T de Wilcoxon<br />

Z o<br />

=<br />

n<br />

T<br />

−<br />

4t. Prendre decisió:<br />

• Taules de la T de Wilcoxon<br />

n<br />

Si T > Ts (α, n) → Rebutjo H 0 → p<br />

Si T ≤ Ts (α, n) → No rebutjo H 0 → NC<br />

• Taules de la llei normal (n > 25)<br />

Si z >z α → Rebutjo H 0 → p<br />

Si z ≤ z α → No rebutjo H 0 → NC<br />

5è. Conclusions<br />

( n + 1)<br />

( n + 1)<br />

( 2n<br />

+ 1)<br />

24<br />

4<br />

Si n > 25

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