In: Statistics and Probability
Calculate the median for the blood HDL levels of 43 patients with following frequency distribution?
HDL (mg/dl): 20, 9, 25, 50, 40, 80
No. of patients: 6, 4, 16, 7, 8, 2
Solution:
As data is in the form of frequency distribution, we have to calculate weighted median.
Rearrange distribution so as to get ordered HDL frequency distribution and calculate the cumulative frequency as well.
HDL (mg/dl), xi : 9, 20, 25, 40, 50, 80.
No. of patients, fi : 4, 6, 16, 8, 7, 2.
Cumulative frequency (c.f): 4, 10, 26, 34, 41, 43.
Total patients are 43, so:
N/2 = ∑fi / 2
= 43/2
= 21.5
So, the middle result in the ordered frequency table will be 22nd term.
From the above ordered frequency distribution, 22nd term has value = 25.
Thus, the median blood HDL level in the patients' is 25 mg/dl.
The median blood HDL level in the patients' is 25 mg/dl.