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Age, Period, or Birth Cohort: What Determines Demographic Differences in Seafood Consumption?

Age, Period, or Birth Cohort: What Determines Demographic Differences in Seafood Consumption?.

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Age, Period, or Birth Cohort: What Determines Demographic Differences in Seafood Consumption?

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  1. Age, Period, or Birth Cohort: What Determines Demographic Differences in Seafood Consumption? Joachim ScholdererMAPP, The Aarhus School of Business, DenmarkEiliv LundInstitute of Community Medicine, University of Tromsø, Norway Torbjørn TrondsenNorwegian College of Fishery Science, University of Tromsø, Breivika, Norway www.fishmarketing.com

  2. Background • Earlier studies: • H1: Young people consume less fish than older people • Prognosis: less consumption in future • H2: People increases fish consumption as they grow older • Prognosis: Fish consumption do not decrease even if young people now a day consume less fish than earlier generations • Increasing elderly population: consequences for seafood consumption? T. Trondsen. Age, cohort and period.

  3. Aim of study • The aim of the present study was to separate the effects of “age” on fish consumption • as a cohort effect • a period effect • an effect of biological ageing T. Trondsen. Age, cohort and period.

  4. Possible implications of the underlying cause • If cohort • a general ageing of society would imply decreasing consumption levels over time as older, high-consumption cohorts are dying away • If period • increase or decrease over time would depend on the existence and shape of a general trend · If biological age • the ageing of society would imply increasing consumption levels over time T. Trondsen. Age, cohort and period.

  5. Fat fish Lean fish Processed fish Birth year 1996 2001 % change 1996 2001 % change 1996 2001 % change 1951-1955 2.3 2.5 6.9 4.4 3.6 -17.2 3.0 4.4 46.5 1956-1960 1.8 2.3 26.2 4.0 3.4 -15.6 3.2 4.6 44.5 1961-1965 1.9 2.0 8.2 3.8 3.2 -16.3 3.2 4.8 47.6 1951-1965 2.1 2.3 8.5 4.1 3.4 -16.4 3.1 4.6 46.2 Observed means seafood dinners per month T. Trondsen. Age, cohort and period.

  6. Methods • Panel data from the Norwegian Women and Seafood Consumption Study (NOWAC) • Cohorts selected women born 1951-1966 • Survey questionnaires mailed to a stratified random sample from the Norwegian population registry in 1996 and 2001 • Representative for the female Norwegian population • Complete data sets for both periods were obtained from N = 4590 respondents • Data analyzed by means of multivariate linear models T. Trondsen. Age, cohort and period.

  7. 1996 2001 Fat fish b -.044 -.045 SE .008 .008 F -5.718, -5.914 p < .001) < .001 Lean fish b -.062 -.047 SE .010 .009 t -6.012 -5.198 p < .001 <.001 Processed fish b .023 .029 SE .008 .011 t 3.095 2.731 p < .01 <.001 Results: Cohort effects T. Trondsen. Age, cohort and period.

  8. 1996 2001 Fat fish Meals/month 2.06 2.25 SE 0.035 0.035 Lean fish Meals/month 4.05 3.39 SE 0.041 0.047 Processed fish Meals/month 3.2 4.6 SE 0.034 0.048 Sum fish consumption Meals/month 9.28 10.25 SE 0.075 0.087 Results: Period effects Pct +9,2 -16,3 +47% +10,5 T. Trondsen. Age, cohort and period.

  9. Results: Cohort vs. Biological Age Cohort Biological age T. Trondsen. Age, cohort and period.

  10. Discussion and Conclusion • Processed fish consumption is rising in Norway. • Consumption levels were found to be higher in later birth cohorts, among younger people in general, and in later consumption periods. • The conclusion remains invariant under all different interpretations of the age-period-cohort problem. T. Trondsen. Age, cohort and period.

  11. Discussion and Conclusion • Lean fish consumption is falling in Norway • Consumption levels were found to be lower • in later birth cohorts • among younger women in general • in later consumption periods • The conclusion remains invariant under all different interpretations of the age-period-cohort problem T. Trondsen. Age, cohort and period.

  12. Discussion fat fish consumption • Remains ambiguous • Fat fish consumption has increased totally and for each birth cohort, but not by age • The households in the cohort have also changed T. Trondsen. Age, cohort and period.

  13. Discussion fat fish consumption • Two hypotheses: • (a) an increase over time periods is partially cancelled by a decreasing household size over birth cohorts, leaving a biological age effect as a mere residual • (b) The positive relationship with biological age is the true and only underlying effect neutralizing the effect of changing household size and composition T. Trondsen. Age, cohort and period.

  14. Conclusion • Fish (Fat) fish consumption changes with age and changing size and composition of households • Cohort and age predicts • less lean fish consumption • Increased processed fish consumption • Age predicts • Fat fish consumption • Cohort predicts consumption for fish products in market segments related to households cycles T. Trondsen. Age, cohort and period.

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