1. Research potential of the SAM Giorgio Finella and Rachel Leeser Data Management and Analysis Group Email. giorgio.finella@london.gov.ukgiorgio.finella@london.gov.uk or rachel.leeser@lonfdon.gov.uk

2. Contents The strengths of the SAM compared to: Census Standard and Commissioned Tables SAR family Longitudinal Study Non Census datasets Uses for the SAM Sampling errors – comparison Conclusions

3. Key strengths of SAM Sample Size, Sample Size, Sample Size 5% Local Authority Geography 268 LAs over 5,000 residents 135 LAs between 3 and 5,000 30 LAs between 1,200 and 3,000 Quicker than commissioning tables Cheaper than a bespoke survey

4. Sample sizes 49,000Birmingham 36,000Leeds 29,000Glasgow 26,000Sheffield 24,000Bradford 22,000Liverpool 20,000Manchester 13,000 Newcastle 12,000 Plymouth 5,000 Wyre Forest 5,000 Worcester London Boroughs vary 17,000 Croydon 7,000 Kingston UT

5. Standard and Commissioned Tables Cross tabs religion & ethnicity with all variables Multivariate analysis Commissioned Tables cost £150 - £1000 Timeliness SAM is more versatile SAM one off cost

6. SAR family Once obtained held locally SARi, 3% sample, geography GOR SARh, 1% sample, complex application form, no geography only E&W Available at ONS offices CAMSi, complex application form, time and cost CAMSh, complex application form, time and cost

7. Longitudinal Study Linked Census data from 1971 to 2001. Smaller sample only 1% Examine the same people at two or more censuses Unlikely to be used by Local Authorities on a day to day basis. Of interest migration, LLTI, households & family arrangements

8. Non Census datasets Annual Population Survey / Labour Force Survey smaller sample, excl. Communal Establishments General Household Survey (GHS) GOR geography Family Resource Survey / Household Below Average Income (FRS/HBAI) complex series of files

9. Uses for the SAM Simple univariate of population subgroups Cross tabulations for different geographies More complex cross tabulations Multivariate analysis Exploring Census data prior to commissioning

10. Sampling errors Differences to be expected Standard Errors (SE) = (p*(100-p)/n) p is the percentage calculated and n is the sample size

11. Sampling errors Small sample size – higher degree of variability The SAM sample size is almost ten times the LFS for London in 2001. The percentage of Chinese children born in the UK, a 95 per cent confidence interval for the: SAM is 81 to 87 per cent, ± 3pp, whereas LFS is 83 to 99 per cent, ± 8pp.

12. Conclusions Not always appropriate - Always use the largest sample possible SAM reliable, flexible, robust, ease of use, low cost and no non-response bias Speed of access unparalleled Full report available from CCSR