BCS70 – Child of CM (Multi-Age) – BAS Number Skills

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The 1970 British Cohort Study (BCS70) assessed the children of cohort members (CMs) during the study’s age 34 sweep using the Number Skills measure from the British Ability Scales (BAS).

When the CM was aged 34, child assessments were conducted with the cohort member’s children. Each of the CM’s eligible children were asked to complete three exercises designed to measure a range of verbal and numerical abilities. Although dependent on the child’s age and abilities, each set of exercises was expected to take an average of 20 minutes to complete.

The BAS Number Skills measure was administered as part of a set of ‘School Age’ exercises (for children aged between 6 and 16 years and 11 months). Details on this measure and the data collected are outlined in the table below.


Domain:School knowledge - basic competence in arithmetic calculation (achievement scale)
Measures:Acquired computational skills:
Ability to recognise and express the names of numerals
Arithmetic skills
Knowledge and understanding of basic number concepts
CHC:Gq (Quantitative Knowledge)
Administrative method:The numerical tasks were presented in a specially designed booklet.
Procedure:The child was asked to perform basic arithmetic operations with whole numbers, common fractions and decimals and to convert fractions to decimals and percentages. The task was arranged in six blocks (A to F); the first four blocks consisted of eight items each, and the last two blocks had seven items each. The number of blocks a child attempted depended on the child's age and performance This assessment was designed to be used with children aged from 6 years to 17 years and 11 months. And for children aged 5:0 to 5:11 of above average ability.
Link to questionnaire:https://cls.ucl.ac.uk/wp-content/uploads/2017/07/BCS70-2004-Guide-to-Child-Assessments.pdf (opens in new tab)
Scoring:46 items, starting and stopping points were different based on child's age. Start at age equivalent item, if < 5 were correct then starts on easier block until 5 or more items were correct. If 5 or more correct, then child moves to next batch until 3 or fewer items in a black were incorrect.
Item-level variable(s):basns01 - basns08 (age 5:0 - 7:11)
basns09 - basns16 (age 8:0 - 9:11)
basns17 - basns24 (age 10:0 - 11:11)
basns25 - basns32 (age 12:0 - 17:11)
basns33 - basns46
Total score/derived variable(s):basnsR (raw score)
basnsA (ability and age adjusted)
Age of child (months):Mean = 117.65, SD = 32.95, Range = 72 - 203
Descriptives:basnsR (raw score)basnsA (ability and age adjusted)
N2,2402,240
Range0 - 2710 - 208
Mean10.68107.36
SD3.9331.59
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Other sweep and/or cohort:None
Source:Elliott, C. D., Smith, P., & McCulloch, K. (1996). British Ability Scales Second Edition (BAS II). Administration and Scoring Manual. London: Nelson.
Elliott, C. D., Smith, P., & McCulloch, K. (1997). British Ability Scales Second Edition (BAS II). Technical Manual. London: Nelson.
NB. Layout and symbols of the tests were adapted from BAS II to reflect change in curriculum since version of BAS was produced.
Technical resources:Parsons, S., Bynner, J., & Foudouli, V. (2005). Measuring basic skills for longitudinal study: the design and development of instruments for use with cohort members in the age 34 follow-up in the 1970 British Cohort Study. NRDC: London.
Parsons, S. (2006). British Cohort Study 2004 Follow up: Guide to Child Assessment Data, CLS Working Paper.
Reference examples:Cooksey, E., Joshi, H., & Verropoulou, G. (2009). Does mothers' employment affect children's development? Evidence from the children of the British 1970 Birth Cohort and the American NLSY79. Longitudinal and Life Course Studies, 1(1), 95-115.
Crawford, C., Goodman, A., & Joyce, R. (2011). Explaining the socio-economic gradient in child outcomes: the inter-generational transmission of cognitive skills. Longitudinal and Life Course Studies, 2(1), 77-93.
Mallows, D. (2013). The intergenerational transfer of numeracy skills. Institute of Education, University of London.

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This page is part of CLOSER’s ‘A guide to the cognitive measures in five British birth cohort studies’.