Page 81

ing at the pairwise correlations between the individual exams (FIGURE 6 .3), which were all highly significant (p < 10-10 in all cases). While we found the average pairwise correlation to be relatively strong (ρ= 0.60), correlations involving practical 1 (Cell) were lower (ρ = 0.51 on average) than other comparisons (ρ = 0.68 on average), suggesting that practical 1 (Cell) is affected by more stochasticity. This is further confirmed by the correlations of the scores obtained in practical and the theoretical exam ( FIGURE 6 .4), which were again all highly significant ( p < 10 -15 in all cases). The average correlation was found to be very high (ρ= 0.68) and actually higher than the average pairwise correlations among practical exams, suggesting that the scores obtained in an individual practical exam are more stochastic than those in the theoretical exam as a whole. As expected, practical 1 (Cell) showed the weakest correlation with the theoretical scores (ρ = 0. 56) and practical 4 (Syst) the strongest (ρ = 0.79).

Cell vs. Syst

1.0

Cell vs. Ethno

1.0

1.0

Cell vs. Plant

0.8

0.0

0.2

0.2

0.0

0.6 Plant

0.8 0.6

Syst

0.4 0.2

1.0

0.0

● ●●

0.2

0.0

0.2

0.4

0.6 Plant

1.0 0.8

ρ = 0.74

0.6

0.8

1.0

0.8

●● ● ● ● ● ●● ● ● ●● ●●● ● ● ●● ● ● ● ●●●●●●● ● ● ● ● ● ● ● ●●● ●● ● ●● ● ● ●● ● ●● ●●● ● ●● ●● ●● ● ●●● ●● ● ●● ● ● ● ● ● ● ● ● ●● ● ● ●●● ●●●● ● ●●● ●●● ● ●● ● ● ● ● ● ●●●● ● ●● ● ● ●● ● ●●●● ● ●● ●●● ●● ● ● ● ●● ● ● ●● ●● ●● ●● ● ● ● ●●● ●● ● ● ● ● ● ● ●● ● ●● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ●● ● ●● ●●● ● ● ● ● ● ● ● ● ●● ● ●● ● ● ●● ●● ●● ●● ● ● ●● ● ● ● ● ●● ●

Syst

0.4

0.6

0.8 1.0

0.4

Ethno vs. Syst ●

0.6

1.0 0.8

● ●● ●

ρ = 0.51

●●

Cell

● ● ●● ● ● ● ● ●● ●●●●● ● ● ●●● ●● ●● ● ●● ● ● ● ●● ● ● ● ● ● ●● ●●● ● ●● ●●●● ●● ●● ●● ● ● ● ●● ●●● ● ●●●● ● ● ● ● ●●●●●● ●● ● ● ●●● ●● ●● ● ● ● ● ● ●● ● ●● ● ● ●●● ● ● ●● ●● ● ● ● ● ● ●● ● ● ● ● ●●●●●● ● ● ● ● ●● ● ● ● ●●●● ●● ● ●● ● ●●●●● ●● ● ● ● ● ●● ●● ● ● ● ●●●● ● ●● ● ●● ●● ●● ●● ● ● ●● ● ● ● ●●● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ●●● ● ● ● ● ● ● ● ● ● ● ●

0.2

Syst

ρ = 0.65 0.4

0.8

Plant vs. Syst

0.0

1.0 0.6 0.4 0.2

Ethno

0.8

● ● ● ● ● ●● ● ●● ● ● ● ●● ● ● ● ● ●●●● ● ● ● ● ●● ● ● ●● ●● ●● ● ● ● ● ● ● ● ●● ● ●● ● ●● ● ●● ●● ● ●●●● ● ●●●● ● ● ●● ● ● ● ● ● ●●● ● ●● ●● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ●● ● ● ● ● ● ● ●●● ●● ● ●●●●● ● ●●● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ●● ● ● ● ●●● ● ●● ●● ●●●●● ● ● ●●●● ● ● ● ● ● ●●●● ● ●● ●● ● ● ● ● ● ● ● ● ● ●●● ● ●● ● ● ● ● ●●● ● ● ●● ● ●● ● ●● ● ● ● ● ● ● ●● ● ● ●● ● ●● ● ● ●● ● ● ● ●

0.0

0.6

Cell

Plant vs. Ethno

● ●

0.4

0.0

0.0

1.0

● ● ●● ●● ● ● ● ● ● ● ●● ●● ●● ● ●● ●● ● ●● ●● ●● ● ● ●● ● ●● ● ● ● ● ● ● ●● ● ● ● ●● ●● ●● ●● ● ● ●● ● ● ● ● ●● ● ● ●● ● ● ● ●● ● ● ●● ● ● ● ● ●●● ● ● ● ● ●●●● ●●● ●● ● ●● ● ● ● ● ●● ● ● ●● ●● ● ●● ● ●● ●● ● ●● ● ● ● ● ●● ● ● ●●● ● ● ● ● ● ●● ● ●●● ● ● ●● ● ●● ●● ● ● ●● ●● ● ● ● ●● ● ● ● ●●● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ●● ● ● ● ● ●● ● ● ● ● ●● ●● ● ● ● ● ● ● ● ● ●

0.4

0.6 Cell

ρ = 0.43

● ●

0.2

0.4

● ● ●● ● ● ● ● ● ●●●● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ●● ● ● ●●●●●● ● ●● ● ●●● ● ● ●●● ● ● ●●●●● ● ●●● ● ●● ● ● ●● ● ● ● ● ●● ● ● ●● ● ● ● ●● ● ●● ● ●●●●●●● ●● ● ● ● ●● ●● ● ● ● ●● ● ● ● ● ● ● ● ●●● ● ● ●● ● ● ● ● ● ● ● ●● ● ●●● ●● ● ●● ●● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ●● ● ● ● ● ●● ● ●● ● ●● ● ● ● ●● ●● ● ● ●● ● ● ● ● ● ● ● ●●● ● ● ● ●● ● ● ● ●● ●● ● ● ● ●● ● ● ●●

1.0

● ● ● ●

0.0

0.2

0.6

0.8

ρ = 0.59

0.0

0.4 0.2

Ethno

0.6 0.4

● ● ● ● ● ●● ●● ● ● ● ● ● ●● ●● ●●● ● ● ● ● ● ●● ● ●● ● ●● ●● ●● ●● ● ● ● ●● ●●●● ●● ● ● ● ● ● ● ●● ●● ●● ● ●● ● ●● ●● ●● ●● ●● ● ● ●● ● ●● ● ●● ● ● ●● ● ● ● ●●● ● ●● ● ● ● ● ●●●● ● ● ● ● ● ●● ● ● ● ● ● ●●●●● ● ● ● ● ● ● ● ●● ● ● ● ●● ●●● ● ●● ● ● ● ● ●●●● ●● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ●● ● ● ●● ●● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ●● ● ● ● ● ● ● ● ●● ● ● ● ●● ● ● ● ● ●● ● ● ● ● ● ● ● ●

0.0

0.2

Plant

0.8

0.0

0.2

ρ = 0.66

●●

0.4

0.6

0.8

1.0

Ethno

FIGURE 6 .3  Pairwise correlations of practical exam scores:

Each dot represents the scores obtained by a participant in two different practical exams. Purple lines indicate linear regression results and Pearson correlations coefficients (ρ) are given in the lower right corner of each panel.

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IBO 2013 Final Report  
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