Could you please give us an example on how we calculate the quartiles (Q1 or Q3)?

Quartiles in statistics are values that divide your data into quarters. Q1 is the median of the lower half of a data set assuming the data is in increasing order. Q3 is the median of the upper half of the data set. So 75% of a data set falls below Q3 and 25% above it. To determine any of the quartiles, we need to arrange the data in order first. After this we need to apply the upper quartile formula, which is:

Q3 = ¾(n + 1)th Term.

Note that n is the number of data value. Also note that the above formula doesn’t give the value of Q3 but the position of Q3. Accordingly from the list of ordered data, the Q3 can be determined.