(****
 * Module Statistics shows the statistics that have to be programmed into the Grader.
 * The Grader uses a column of data to find the mean, median, and standard deviation
 * to produce a Bell curve to view the distribution of the column GradedItem.
 *)



module Statistics;
	from Gradesheet import Gradesheet;
	
	object BellCurve is 
		components: mean and stDev;
		description: (* 
			Takes the mean and stDev of a ColumnSelected or defaults to the 
			Final Grade column. Calculates within 3 standard deviations away
			from the mean and displays under the curve and outside in a chart.
		*);
	end BellCurve;

	
	object mean is real
		components: GradedItem;
		description: (*
			Takes all values in a column selected by the user, and sums the 
			values and then divides by the total amount of GradedItems in 
			the column.
		*);
	end mean;


	object median is real
		components: GradedItem;
		description: (*	
			Takes all values in a column selected by the user, and orders the 
			values lowest to highest.  If the selected GradedItems are an odd
			number of items, the middle value is selected.  If even, the middle
			two values are averaged to find the median.
		*);
	end median;
	
	
	object stDev is real
		components: GradedItem;
		description: (*	
			Finds the standard deviation for a set of data in a GradedItems
			column.  This calculation is too advanced for programming in 
			RSL, therefore the programmers must use a language specific tool
			to get the Standard Deviation.
		*);
	end stDev;
end Statistics;