The document describes four common sampling methods: (A) random sampling which selects a random sample from a complete population list and is free from bias but not all members can be accessed, (B) stratified sampling which divides the population into strata and randomly samples from each proportionally, allowing a representative sample but requiring accurate population data, (C) systematic sampling which selects every kth member from a population list, making it easier than random sampling for large populations but risking bias if the list has a pattern, and (D) quota sampling where the interviewer selects the sample based on quotas for each stratum, having a lower cost than random sampling but introducing bias from non-random selection.

1. SAMPLING METHODS<br />(A) RANDOM SAMPLING<br />(EXP) <br />List the (members of the population), say from 1 to (N)<br />And make a random selection of (n- sample)<br />(NOTE) Suitable for relatively small population and the sampling frame is complete and up-to-date.<br />(ADVANTAGES) <br />Truly random<br />Free from bias<br />(DISADVANTAGE)<br />Not able to get access to some members who have been chosen for the sample.<br />(B) STRATIFIED SAMPLING<br />(EXP) <br />Divide the (members of the population) into different strata based on (age/ ethnic/ gender)<br />Find the proportion [%] among the strata <br />Calculate sample size for each stratum according to proportion [%] <br /><< % × n>><br />Select from each stratum using random sampling<br />(ADVANTAGE)<br />Likely to give a good representative sample of the population<br />(DISADVANTAGES)<br />Can be expensive<br />Require precise and accurate information about population<br />(C) SYSTEMATIC SAMPLING<br />(EXP)<br />List the (members of the population)<br />Select every k = (population)/(sample) = (sampling interval)th (member from the list),<br />Select until obtain the required sample.<br />(ADVANTAGES)<br />Easier to conduct as compared to other types of sampling<br />Suitable for large samples<br />(DISADVANTAGES)<br />Not always possible to (line up/ obtain a list) of all the members of the population<br />Bias if the list obtained follows a periodic or cyclic pattern<br />(D) QUOTA SAMPLING<br />(EXP)<br />QUOTACHOICE OF SAMPLE BASED ON OWN PREFERENCE<br />Divide the (members of the population) into different strata based on (age/ ethnic/ gender)<br />Find the proportion [%] among the strata <br />Calculate sample size for each stratum according to proportion [%] <br /><< % × n>><br />Select from each stratum based on own preference<br />(ADVANTAGES)<br />Lower cost<br />Information can be corrected easily<br />(DISADVANTAGES)<br />Non-random<br />Bias as interviewer may select those who are easiest to interview<br />