Date Reale

Datele sunt luate de pe http://www.rossmanchance.com/iscam/files.html unde se gasesesc fisiere ISCAM (Investigating Statistical Concepts, Applications, and Methods), si reprezinta:

- 507 de cazuri reprezentand oameni de varsta medie (18-60) ei sunt impartiti in doua grupuri date de sexul lor (barbat sau femeie);

- Sunt date rezultatele obtinute pentru weight si height (greutatea si inaltimea acestora).

Probleme propuse:

1. Cele doua grupuri prezinta diferente semnificative ale greutatii?

2. Cele doua grupuri prezinta diferente semnificative ale inaltimii?

3. Exista o relatie intre inaltime si greutate?

Teste semnificative pentru evidentierea diferentelor intr grupuri

Folosim testul student (t)

H: cele doua grupuri au aceeasi medie pentru greutate?

R: nu au

Ipoteze:

- presupunem cazurile independente, vin din populatii cu distributie normala, au aceeasi dispersie

Verificam daca ipotezele sunt satisfacute de datele pe care le investigam:

weightM<-iq.data[iq.data[,"gender"]=="male","weight"]

- pastreaza rezultatele obtinute pt greutate barbatilor.

> weightM

[1] 65.6 71.8 80.7 72.6 78.8 74.8 86.4 78.4 62.0 81.6 76.6 83.6

[13] 90.0 74.6 71.0 79.6 93.8 70.0 72.4 85.9 78.8 77.8 66.2 86.4

[25] 81.8 89.6 82.8 76.4 63.2 60.9 74.8 70.0 72.4 84.1 69.1 59.5

[37] 67.2 61.3 68.6 80.1 87.8 84.7 73.4 72.1 82.6 88.7 84.1 94.1

[49] 74.9 59.1 75.6 86.2 75.3 87.1 55.2 57.0 61.4 76.8 86.8 72.2

[61] 71.6 84.8 68.2 66.1 72.0 64.6 74.8 70.0 101.6 63.2 79.1 78.9

[73] 67.7 66.0 68.2 63.9 72.0 56.8 74.5 90.9 93.0 80.9 72.7 68.0

[85] 70.9 72.5 72.5 83.4 75.5 73.0 70.2 73.4 70.5 68.9 102.3 68.4

[97] 65.9 75.7 84.5 87.7 86.4 73.2 53.9 72.0 55.5 58.4 83.2 72.7

[109] 64.1 72.3 65.0 86.4 65.0 88.6 84.1 66.8 75.5 93.2 82.7 58.0

[121] 79.5 78.6 71.8 116.4 72.2 83.6 85.5 90.9 85.9 89.1 75.0 77.7

[133] 86.4 90.9 73.6 76.4 69.1 84.5 64.5 69.1 108.6 86.4 80.9 87.7

[145] 94.5 80.2 72.0 71.4 72.7 84.1 76.8 63.6 80.9 80.9 85.5 68.6

[157] 67.7 66.4 102.3 70.5 95.9 84.1 87.3 71.8 65.9 95.9 91.4 81.8

[169] 96.8 69.1 82.7 75.5 79.5 73.6 91.8 84.1 85.9 81.8 82.5 80.5

[181] 70.0 81.8 84.1 90.5 91.4 89.1 85.0 69.1 73.6 80.5 82.7 86.4

[193] 67.7 92.7 93.6 70.9 75.0 93.2 93.2 77.7 61.4 94.1 75.0 83.6

[205] 85.5 73.9 66.8 87.3 72.3 88.6 75.5 101.4 91.1 67.3 77.7 81.8