public void avgGroupChange() throws IOException
    {
        System.out.println( "Enter file name: " );
        String filename = scan.nextLine().trim();
        File file = new File( filename );
        Scanner scan2 = new Scanner( file );

        int groups = scan2.nextInt();
      	int currentGroup = 0;
        int groupSize = 0;
	int start, end;

        while ( scan2.hasNextLine() )
        {
            int groupSize = scan2.nextInt();
	currentGroup++;
	int startSum;
	int endSum;
	for(int i = 0; i < groupSize; i++) {
		start = scan2.nextInt();
		end = scan2.nextInt();
		startSum += start;
		endSum += end;
	}
	if(groupSize > 0) {
		double startAvg = (startSum / groupSize);
		double endAvg = (endSum / groupSize);
	}
           System.out.println( "Group" + currentGroup + '\t' + groupSize + "subjects" );
           System.out.println( "average starting cholesterol:" + '\t'
           	+ startAvg );
            System.out.println( "average final  cholesterol:" + '\t'
                	+ endAvg );
            System.out.println( "change in cholesterol:" + '\t' + (endAvg - startAvg) );
        }
        System.out.println( "Done with processing." );

    }