Why we measure period fertility
Why we measure period fertility
Four reasons for measuring period fertility are distinguished: to explain fertility time trends, to anticipate future fertility, to construct theoretical models and to communicate with non-specialist audiences. The paper argues that not all measures are suitable for each purpose, and that tempo adjustment may be appropriate for some objectives but not others. In particular, it is argued that genuine timing effects do not bias or distort measures of period fertility as dependent variable. Several different concepts of bias or distortion are identified in relation to period fertility measures. Synthetic cohort indicators are a source of confusion since they conflate measurement and forecasting. Anticipating future fertility is more akin to forecasting than to measurement. Greater clarity about concepts and measures in the fertility arena could be achieved by a stronger emphasis on validation. Period incidence and occurrence-exposure rates have a straightforward interpretation. More complex period fertility measures are meaningful only if a direct or indirect criterion can be specified against which to evaluate them. Their performance against that criterion is what establishes them as valid or useful.
fertility, period fertility, measurement, tempo adjustment, timing, validation, forecasting
Southampton Statistical Sciences Research Institute, University of Southampton
Ní Bhrolcháin, Máire
c9648b58-880e-4296-a173-7241449e0078
28 June 2007
Ní Bhrolcháin, Máire
c9648b58-880e-4296-a173-7241449e0078
Ní Bhrolcháin, Máire
(2007)
Why we measure period fertility
(S3RI Applications & Policy Working Papers, A07/04)
Southampton, GB.
Southampton Statistical Sciences Research Institute, University of Southampton
42pp.
Record type:
Monograph
(Working Paper)
Abstract
Four reasons for measuring period fertility are distinguished: to explain fertility time trends, to anticipate future fertility, to construct theoretical models and to communicate with non-specialist audiences. The paper argues that not all measures are suitable for each purpose, and that tempo adjustment may be appropriate for some objectives but not others. In particular, it is argued that genuine timing effects do not bias or distort measures of period fertility as dependent variable. Several different concepts of bias or distortion are identified in relation to period fertility measures. Synthetic cohort indicators are a source of confusion since they conflate measurement and forecasting. Anticipating future fertility is more akin to forecasting than to measurement. Greater clarity about concepts and measures in the fertility arena could be achieved by a stronger emphasis on validation. Period incidence and occurrence-exposure rates have a straightforward interpretation. More complex period fertility measures are meaningful only if a direct or indirect criterion can be specified against which to evaluate them. Their performance against that criterion is what establishes them as valid or useful.
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46437-01.pdf
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Published date: 28 June 2007
Additional Information:
This paper has been superseded by S3RI working paper A08/05.
Keywords:
fertility, period fertility, measurement, tempo adjustment, timing, validation, forecasting
Identifiers
Local EPrints ID: 46437
URI: http://eprints.soton.ac.uk/id/eprint/46437
PURE UUID: d9db4609-9463-4192-b726-421cc6d7e81b
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Date deposited: 28 Jun 2007
Last modified: 11 Dec 2021 16:34
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Author:
Máire Ní Bhrolcháin
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