Tuesday, 7 March 2017

[7 March - Just in Time Learning] It's vague! How well is well done?

This morning, we received our Level Test 1 papers. How well did the class do?
Well... how "well" is "well"? It's vague.

To add clarity, we use 3 measures to help us interpret data - Mode, Median and Mean
(a topic that we'll do into greater details in Term 2/3).

Using this example (before we look into the class data), we learnt how to interpret the table (known as the frequency table) and draw out what is the mode, median from the table. Mean is what we referred to as "average" in primary school.

Simply put across:

  • Mode: The most frequently occurred item
  • Median: The value of the middle item
    • The items have to be arranged in ascending/ descending order (of the values it carries)
    • If there are odd number of items, e.g. 13, then the middle item is at the 7th position (6 before and 6 after this item). The value of the 7th position item is the median.
    • If there are even number of items, e.g. 20, then the items would be divided into 2 equal halves. So, we find the average of the value in the 10th and 11th position.
  • Mean: Same as the "average" we learnt in primary school
    • Find the sum of all the values of the items, then divide by the number of items.

With the above knowledge, given the TOTAL Grade Score,

  • we can find out the mean subject grade of the class
  • we are able to find the maximum (i.e. the largest possible) number of students who can score Grade 1
  • we can find, if everybody scored either A1 or A2, what is the number of students who scored A1 or A2 

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