Stationarity of seasonal patterns in weekly agricultural prices

  1. José Juan Cáceres Hernández
  2. Carmen Gloria Martín Rodríguez
Spanish journal of agricultural research

ISSN: 1695-971X

Year of publication: 2018

Volume: 16

Issue: 3

Pages: 2

Type: Article

Export: RIS
DOI: 10.5424/sjar/2018163-12937 DIALNET GOOGLE SCHOLAR lock_openOpen access editor


JCR (Journal Impact Factor)

  • Year 2018
  • Journal Impact Factor: 1.035
  • Best Quartile: Q2
  • Area: AGRICULTURE, MULTIDISCIPLINARY Quartile: Q2 Rank in area: 28/57 (Ranking edition: SCIE)

SCImago Journal Rank

  • Year 2018
  • SJR Journal Impact: 0.391
  • Best Quartile: Q2
  • Area: Agronomy and Crop Science Quartile: Q2 Rank in area: 146/363


  • Year 2018
  • CiteScore of the Journal : 1.6
  • Area: Agronomy and Crop Science Percentile: 54

Journal Citation Indicator (JCI)

  • Year 2018
  • Journal Citation Indicator (JCI): 0.39
  • Best Quartile: Q3
  • Area: AGRICULTURE, MULTIDISCIPLINARY Quartile: Q3 Rank in area: 39/54


Weekly series of agricultural prices usually exhibit seasonal variations and the stationarity of these variations should be taken into account to analyse price relationships. However, unit root tests at seasonal frequencies are unlikely to have good power properties. Furthermore, movements in actual price series are often not as expected when unit roots are present. Therefore, stationarity tests at seasonal frequencies also need to be applied. In this paper, a procedure to test for the null hypothesis of stationarity at seasonal frequencies was extended to the weekly case. Once critical values were obtained by simulation exercises, unit root and stationarity tests were applied to weekly retail prices of different agricultural commodities in Spain. The most relevant finding was that many unit roots that seasonal unit root tests failed to reject did not seem to be present from the results of seasonal stationarity tests, whereas seasonal unit root tests led to the rejection of some unit roots that seemed to be present according to the results of seasonal stationarity tests. In conclusion, unit root tests should be complemented with stationarity tests before making decisions about the behaviour of seasonal patterns.

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