1st NRC Meeting, October 2006, Amsterdam 1 Sampling: Next Steps

1st NRC Meeting, October 2006, Amsterdam 2 Overview Sampling responsiblilites Your next tasks as NRCs Preparations for school sample selection Time lines

1st NRC Meeting, October 2006, Amsterdam 3 Sample Selection in ICCS Goal for sample selection in ICCS: Selecting a sample of students and teachers that represents the situation in your country well. meets the IEA standards for sampling precision. meets your research interests. Needed: Adaptation of the international sampling design to the situation in your country.

1st NRC Meeting, October 2006, Amsterdam 4 Sampling Responsibilities Sampling referee (Jean Dumais) : –Advise on sampling methodolgy –Review sampling execution –Resolve possible conflicts IEA Data Processing Center –Provide a sampling preparation manual –Review national sampling plans –Select school samples –Provide within-school sampling software –Compute sampling weights

1st NRC Meeting, October 2006, Amsterdam 5 Sampling Responsibilities: NRCs NRCs: –Provide basic information about school system –Develop national sampling plan –Provide a school sampling frame –Review and approve school sample –Perform within-school sampling

1st NRC Meeting, October 2006, Amsterdam 6 Basic Information Target population –Which grade in your country corresponds to the international desired target population definition? Organization of school system –Schools –Classrooms –Teachers NRC task: provide basic information about school system to DPC.

1st NRC Meeting, October 2006, Amsterdam 7 Coverage Some countries may have reduced population coverage. –Example: Language groups –Example: Geographical regions Limitations in national coverage will be annotated in the IEA publications. NRCs are strongly encouraged to provide full national coverage. NRC task: define categories for reduced coverage.

1st NRC Meeting, October 2006, Amsterdam 8 Exclusions Some parts of the target population may have to be excluded. –Example: special education schools –Example: very small schools Student exclusion rate must be below 5%. NRC task: define categories for reduced coverage and exclusion.

1st NRC Meeting, October 2006, Amsterdam 9 Stratification Stratification: dividing the population into non- overlapping subpopulations prior to sample selection. Purposes: –Increase precision of survey estimates –Ensure proportional representation Examples of stratification variables: –Regions (states, provinces…) –School types (public, private...) NRC task: define stratification variables.

1st NRC Meeting, October 2006, Amsterdam 10 National Options –Example: Over-sampling in some strata –Example: Testing additional populations Larger sample may be needed –Reason: previous surveys showed large clustering effects in some countries. Result: NRC and DPC agree on national sampling plan.

1st NRC Meeting, October 2006, Amsterdam 11 School Sampling Frame A comprehensive list of ICCS-eligible schools. Must contain: –School identification number. –Measure of size (students in grade 8). Should contain: –Number of grade 8 classes. –School name. –Address information. NRC task: provide sampling frame to DPC.

1st NRC Meeting, October 2006, Amsterdam 12 Example of a Sampling Frame No merged cells, no sub-totalsA stratification variable is includedExactly one Excel worksheetVariable description in EnglishKey variables are includedEach school represented by exactly one entry in one row

1st NRC Meeting, October 2006, Amsterdam 13 DPC Task: Selection of School Sample(s) Option 1: Selecting a FT sample in 2007 and an MS sample in –Convenience sample for the FT is possible. –Recent changes in school system can be taken into account. Option 2: Selecting a MS and a FT sample simultaneously in –No overlap between FT and MS schools –Inferences are possible –Standard in IEA surveys Second option is the preferred one.

1st NRC Meeting, October 2006, Amsterdam 14 Sampling Time Lines January 2007: Agreement on all national sampling plans. March 2007: All school sampling frames finalized. June 2007: All FT and MS school samples selected and approved.

1st NRC Meeting, October 2006, Amsterdam 15 ???must we cover this??? Within-school sampling?? Participation rates?? Weighting?? Standard error estimation??

1st NRC Meeting, October 2006, Amsterdam 16 Country Consultations During this meeting, individual country consultations between you and the DPC staff will be held. We would like to talk with each of you! Please sign up!

1st NRC Meeting, October 2006, Amsterdam 17 Thank you! Contact: Olaf Zuehlke Sabine Meinck Telephone: +49/40/ Fax: +49/40/