[1] Introduction to Survey Sampling Frame
and Survey Error

(1) How to collect data ?

Survey

Questionnair

Interview

Social listenning

(2) Census VS Sample Survey

1. Census

2. Survey

Obtain data from a population

Gather information from a sample

(3) Parameter VS Statistic

Numerical measure

1. Parameter

2. Statistic

Measure calculated for a population

Measure calculated for a sample

(4) What is a survey ?

  1. Gathered mainly be asking people questions
  1. Typically collected from a sample
  1. Collected by

1. Interview administered method

2. Self-administered method

(5) What do you need to know to design a survey ?

  1. The target population
  1. The sampling frame
  1. The sample design
  1. The mode of data collection
  1. Ongoing survey or One-time survey

Terminology

1. Target population ประชากรเป้าหมาย

2. Sampling frame กรอบตัวอย่าง

3. Sample or element หน่วยตัวอย่าง

Space + Time

Set of things of interest

List and procedure used to identify an element in the target population

Fundamental unit in the population

Different unit ex. person or household

(6) Two approaches to survey sampling

1. Probabilitiy samples

2. Non-probability samples

A know probability of selection

Unknow probability of selection

Randomness or Chance

Judgment

Example

  1. Simple random sampling
  1. Cluster sampling
  1. Startified random sampling
  1. Systematic sampling

Example

1. Snowball samples

2. Quota samples

3. Convenience samples

Start with one person to find other people [Respondent driven sampling]

People who are the easiest to get participate

Problems

Problems

Problems

No prob. mechanism for inital selection

No guarantee that other characteristics will accurately reflect the population

No prob. mechanism for inital selection

No guarantee that other characteristics will accurately reflect the population

The number of people with certain characteristics meet predetermained quotas

No prob. mechanism for inital selection

Miss people with certain charateristics

Homeless, HIV+

Education, Race

Volunteer, Research opportunity

Notation

N

n

Y

y

i

Number or elements in your population

Number of elements in your sample

Population value for survey variable of interest

Sample value for survey variable of interest

Counter for units in the sample or population

Sampling Fraction

f = n/N

(7) Target VS Frame population

1. Frame

2. Target population

Set of materials used to designate a sample of units

Set of households, people or businesses of interest for inference

(8) Mapping

Reality

Ideal

[0.] Perfect mapping

[i.] Element in the target population that is not on the sampling frame

[ii.] Sampling frame contains an element that does not exist in the target population

[iii.] Target population Elements appears more than one on sampling frame

[iv.] More than one target population elements represented by one sampling frame element

[v.] Many to many matching

one-to-one mapping

one-to-zero mapping

zero-to-one mapping

one-to-many mapping

many-to-one mapping

many-to-many mapping

Problems

Solution

Zero chance of selection

Supplemental frames

Problems

Solution

Problems

Solution

Problems

Solution

Problems

Solution

Ineligible units, Foreign units, or Blanks

Duplicates: Non-EPSEM

Screening is needed to dertermine this

Rejecting blank

Smaller sample size

Adjust the sampling rate

m = n(1-pb)

pb

n

m

estimated proportion of blank frame elemants

desired final sample size of population elements

the number of frame elements to select

Remove from list before selection

Unequal probability of selection weights

EPSEM

Euqal Probability Selection Method

f = n/N

Weighting IIllustration

1. Unweighted mean

2. Weighted mean

Non-EPSEM

d(i)

Number of duplicates for a given selected element

1/d(i)

Weight observation for that selection with probability

Clustering

Take all elements within selected clusters

More than one population element can be selected by more than one frame element

Weigting + Subsampling

(9) Survey Error

Error

1. Bias

2. Variance

MSE = (bias)^2 + variance

Systematic error

Variable error

Error that tend to agree

Error that tend to disagree

(10) Types of Error in Survey

1. Coverage error

2. Sampling error

3. Nonresponse error

4. Measurement error

Happens when sampling frame does not match the target population

Occurs due to selective sample instead of the entire population

Occurs when an estimate calculated using only respondents differs from that calculated using the entire sample data

Occurs when the answer from the survey respondent does not match the true answer to the survey question

Ineligible unit

Noncoverage unit

SPF contain individuals who do not belong to the target population [Overcoverage]

SPF not contain all of the members of target population

Sampling bias

Sampling variance

{Coverage bias}

{Nonresponse bias}

Unit nonresponse

Occurs when the sample member does not provide any information

Item nonresponse

Occurs when a respondent fails to answer a survey question

1.Noncontact

2.Refusal

3.Inability to participate

Example

Sensitive question

Inadequate answer

Respondent

Interviewer

Questionnair

Mode of data collection

Either deliberately or unintentionally provide incorrect information

Record responses incorrectly or unintentionally affect answers

Ambiguous or confusing questions

Self-administered modes yield higher levels of sensitive behaviors than Interviewer administered modes

Note

1. Socially desirable question

2. Socially undesirable question

Overreport (+)

Underreport (-)

[2] Simple Random Sampling
and Systematic Sampling