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 groupSize1 = scan2.nextInt();
            currentGroup++;
            int startSum = 0;
            int endSum = 0;
            for ( int i = 0; i < groupSize1; i++ )
            {
                start = scan2.nextInt();
                end = scan2.nextInt();
                startSum += start;
                endSum += end;
            }
            double startAvg = ( startSum / groupSize1 );
            double endAvg = ( endSum / groupSize1 );
            System.out.println( "Group" + currentGroup + '\t' + groupSize1
                + "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." );

    }