Question

CLASS NO: A bank is conducting a customer satisfaction survey, sampling from a list of 25000 active customers. The list includes 15000 general account holders,, 5000 community-care account holders, 2500 premium account holders and 2500 enterprise account holders. The analyst 1. would like to obtain a sample of 500 customers by random sampling. (a) The selection will be made so that there is as close a representation as possible without bias towards any group of customers. (i) What sampling method should be used? (1 mark) (4 marks) (ii) How many community-care account holders should be selected? (b) If systematic sampling is used to select the samples in the general customer account holders (i) What is the sampling interval? (3 marks) (ii) If the first sample taken is 00028, suggest the third and fourth codes for the next two samples. (2 marks)

Answer 1

1.

(a) Bias to all groups of customers is to be minimised.

(i) Stratified random sampling is to be used.

(ii) Number of community-care account holder to be selected=(500/25000)*5000=100.

(b) Number of general account holder to be selected=(500/25000)*15000=300.

(i) Sampling interval=15000/300=50.

(ii) First sample= 00028

Second sample=28+50=00078

Third sample =78+50=00128

Fourth sample=128+50=00178