Agregació de les categories

Vista general

Aquest menú us permet triar l'estratègia d'agregació que s'utilitzarà per a calcular cada qualificació global dels participants per a una categoria de qualificació. Les diferents opcions s'expliquen baix.

Les qualificacions es converteixen primer en valors de percentatge (interval de 0 a 1), després s'agreguen emprant una de les estratègies de baix i finalment es converteixen a l'interval d'elements de la categoria associats (entre la qualificació mínima i la màxima).

The grades are first converted to percentage values (interval from 0 to 1), then aggregated using one of the strategies below and finally converted to the associated category item's range (between Minimum grade and Maximum grade).

Important: Una qualificació buida és simplement una entrada que falta en el butlletí de qualificacions i pot significar coses diferents. Per exemple, pot ser un participant que no ha enviat una tasca, la tramesa d'una tasca encara no qualificada pel professorat, o una qualificació suprimida manualment del butlletí de qualificacions per l'administrador. Us aconsellem que tingueu cura de com interpreteu aquestes "qualificacions buides".

Aggregation strategies

Mean of grades

The sum of all grades divided by the total number of grades.

   A1 70/100, A2 20/80, A3 10/10, category max 100:
   (0.7 + 0.25 + 1.0)/3 = 0.65 --> 65/100

Weighted mean

Each grade item can be given a weight, which is then used in the arithmetic mean aggregation to influence the importance of each item in the overall mean.

   A1 70/100 weight 10, A2 20/80 weight 5, A3 10/10 weight 3, category max 100:
   (0.7*10 + 0.25*5 + 1.0*3)/18 = 0.625 --> 62.5/100

Simple weighted mean

The difference from Weighted mean is that weight is calculated as Maximum grade - Minimum grade for each item. 100 point assignment has weight 100, 10 point assignment has weight 10.

   A1 70/100, A2 20/80, A3 10/10, category max 100:
   (0.7*100 + 0.25*80 + 1.0*10)/190 = 0.526 --> 52.6/100

Mean of grades (with extra credits)

Arithmetic mean with a twist. An old, now unsupported aggregation strategy provided here only for backward compatibility with old activities.

Median of grades

The middle grade (or the mean of the two middle grades) when grades are arranged in order of size. The advantage over the mean is that it is not affected by outliers (grades which are uncommonly far from the mean).

   A1 70/100, A2 20/80, A3 10/10, category max 100:
   0.7 + 0.25 + 1.0 --> 0.25 --> 25/100

Smallest grade

The result is the smallest grade after normalisation. It is usually used in combination with Aggregate only non-empty grades.

   A1 70/100, A2 20/80, A3 10/10, category max 100:
   min(0.7 + 0.25 + 1.0) = 0.25 --> 25/100

Highest grade

The result is the highest grade after normalisation.

   A1 70/100, A2 20/80, A3 10/10, category max 100:
   max(0.7 + 0.25 + 1.0) = 1.0 --> 100/100

Mode of grades

The mode is the grade that occurs the most frequently. It is more often used for non-numerical grades. The advantage over the mean is that it is not affected by outliers (grades which are uncommonly far from the mean). However it loses its meaning once there is more than one most frequently occurring grade (only one is kept), or when all the grades are different from each other.

   A1 70/100, A2 35/50, A3 20/80, A4 10/10, A5 7/10 category max 100:
   mode(0.7; 0.7; 0.25; 1.0; 0.7) = 0.7 --> 70/100

Sum of grades

The sum of all grade values. Scale grades are ignored. This is the only type that does not convert the grades to percentages internally. The Maximum grade of associated category item is calculated automatically as a sum of maximums from all aggregated items.

   A1 70/100, A2 20/80, A3 10/10:
   70 + 20 + 10 = 100/190

[[en:Category aggregation}]]