Name: Promise Ikechukwu Nwogu
Track: Data Analysis
Task: Assignment 1
Q1. What is Quota Sampling Technique?
Quota Sampling Technique is a non-probability sampling. In this sampling, the population is divided into sub groups with unique
characteristics and selected proportionally.
Q2. How can you identify outliers using the IQR method?
Step 1: Sort the data in an ascending order.
Step 2: Locate the Q1 and Q3.
Step 3: Find the IQR (difference between Q3 and Q1).
Step 4: Divide the IQR by 2, NB: Assuming answer is Z.
Step 5: To find Upper and Lower Limit, compute for lower limit; Q1-(IQR*Z), for Upper boundary; Q3+(IQR*Z).
Q3. Data: 25, 30, 28, 35, 40, 45, 38, 36, 42, 39, 41, 44, 37, 33, 31, 29, 34, 46, 43, 40.
Sol.
Arranging in ascending order: 25, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40, 40, 41, 42, 43, 44, 45, 46.
Mean: 736/20 = 36.8
Median: (37+38)/2 = 37.5
Mode: 40
Range: 40-25 = 15
Variance: Mean is 37.5,
Deviation (-11.8, -8.8, -7.8, -6.8, -5.8, -3.8, -2.8, -1.8, -0.8, 0.2, 1.2, 2.2, 3.2, 3.2, 4.2, 5.2, 6.2, 7.2, 8.2, 9.2).
Deviation squared (139.24, 77.44, 60.84, 46.24, 33.64, 14.44, 7.84, 3,24, 0.64, 0.0, 1,44, 4.84, 10.24, 10.24, 17.64, 27.04, 38.44,
51.84, 67.24, 84.64)
Sum of squared deviation = 697.2
Variance: 697.2/20 = 34.86
Standard Deviation: √34.86 = 5.90.
Q1: 31+33 = 32
Q2: 36.8
Q3: 41+42 = 41.5
Interpretation:
 No outliers found in records, i.e., Records are reliable.
 Most frequent sales (Mode) are found around 32-41.
 Standard deviation is low; hence data are not widely spread.
 Skewness is slightly Left Skewed