Explain the measures of central tendency with their merits and demerits.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Define central tendency. A measure of central tendency (an average) is a single value that represents the whole data set. The three common ones are mean, median and mode.
2 · Mean. Definition and formula x̄ = Σx ÷ n (grouped data: Σfx ÷ Σf), with 2-3 merits and 2-3 demerits.
3 · Median. Middle value of sorted data: the (n + 1) ÷ 2 th value; for even n, the average of the two middle values. Merits and demerits.
4 · Mode. Most frequent value; there may be none or more than one. Merits and demerits.
5 · Work one small example. Take 7 Hb values or 8 calorie intakes and find all three averages, showing each step.
6 · Compare in a table. [Table: mean, median and mode against definition, merits, demerits and best use]
7 · Nutrition link. Mean intake is compared with the RDA; the median suits skewed intakes; the mode gives the most common food choice.
8 · Close in one line. No single average is best; choose the one that suits the data and the purpose.
Scoring tip: A correct small sum and a neat comparison table earn more marks than long paragraphs.
