• Survey Research
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• v.7 no.2
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• pp.39-52
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• 2006

Most of Korean survey institutions adopt quota sampling for telephone surveys based on region, gender and age-band. In weekdays, it is well blown that there exist substantial differences in day time in-house rate by individual's socio-demographic attributes. So, quota sampling may induce systematic respondent selection bias. To solve the problem, we propose "time-balanced quota sampling" in which interviewer's call time-band is added as an quota variable. Furthermore, we propose "time-balanced quasi-quota sampling" which is derived by partially relaxing evening time quotas in time-balanced quota sampling. We compare the conventional and the newly proposed quota sampling schemes by drawing Monte Carlo samples from the hypothetical population for which the Korea 2004 time use survey data is assumed.

• KDI Journal of Economic Policy
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• v.34 no.1
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• pp.135-168
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• 2012

This study analyzes ways to detect protest responses (hereafter, PR zero-bid) in the contingent valuation method (CVM). In order to distinguish PR zero-bids from true zero-bids (non-PR zero bids), this study adopts the concept of the implicit willingness to pay employing the Hicksian compensating surplus and the Taylor's 1st order approximation. When a respondent proposes a zero-bid (i.e., WTP=0) and chooses a PR filtering item to indicate that her implicit WTP is not necessary zero, her response is identified as a PR zero bid. PR filtering items falling into the PR zero bids category include the uncertainty of information, distrust in the government and project achievement, disagreement to project plans, discontent with the fairness of public works and their payment method and animosity against the CVM itself. The empirical analysis shows that PR zero bids take place systematically in particular respondent groups: respondents who have never used similar facilities before nor plans to use the facility provided by the public project, the employed, and low income groups. In conclusion, the study suggests that a CVM questionnaire needs to be designed carefully to minimize problems associated with PR zero bids and the potential risks of having sample selection bias should be concerned.