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Table 3 Results of regression models

From: Exploring quality and its value in the Italian olive oil market: a panel data analysis

   OLS models Panel models
Quality clues Variables 2012 2013 2014 OLS pooled Random effects Fixed effects
Product attributes Bottle size 0.5 l − 0.32*** − 0.32*** − 0.30*** − 0.31*** − 0.31*** − 0.32***
Bottle size 0.75 l − 0.35* − 0.48*** − 0.36** − 0.40*** − 0.37*** − 0.37***
Local variety − 0.12* − 0.09 − 0.06 − 0.09*** − 0.05* 0.02
Monovarietal 0.00 0.01 0.09 0.05 0.05 0.06
Light fruity − 0.21* − 0.18* − 0.18 − 0.18*** − 0.14* 0.01
Medium fruity − 0.08 − 0.09 − 0.02 − 0.06 − 0.06 0.01
Farm and production process attributes Olive oil prod < 35 hl 0.13 0.24** 0.06 0.15** 0.14** 0.05**
Olve oil prod 35–134 hl 0.19* 0.26** 0.11 0.20*** 0.17*** 0.09***
Olive oil prod 135–235 hl 0.29* 0.26 0.01 0.17** 0.07 − 0.03
Olive oil prod 236–335 hl − 0.01 0.02 0.05 0.04 0.04 0.00
Hand picking 0.18*** 0.10* 0.12** 0.14*** 0.14*** Omitted
Farm olive oil mill 0.07 0.07 − 0.01 0.05 0.02 Omitted
Cooperative 0.03 0.03 − 0.02 0.01 0.02 Omitted
Purchased olives > 50% 0.01 − 0.06 − 0.07 − 0.03 − 0.03 − 0.08
EVOO from organic farm − 0.03 − 0.09 − 0.09 − 0.07** − 0.02 0.02
Ecosustainability award − 0.02 0.02 0.07 0.03 0.03 0.06
Farm ranking 0.02*** 0.01** 0.02*** 0.02*** 0.02*** 0.03***
Geographical origin attributes North 0.76*** 0.45* 0.55*** 0.57*** 0.56*** Omitted
Center 0.24 0.12 0.26 0.20 0.24 Omitted
geographical indications 0.02 0.09 0.07 0.07* 0.05 0.02
  Cons 1.56** 3.13*** 3.07*** 1.61*** 1.55*** 1.06
Observations 235 269 256 757 757 757
No. of groups      396 396
R^2 0.37 0.32 0.38 0.34 0.33 0.14
Adj R^2 0.32 0.26 0.33 0.32   
RootMSE 0.34 0.34 0.31 0.33   
R^2 within      0.16 0.18
R^2 between      0.34 0.10
Breusch-Pagan LM test      271.57***  
Hausman test RE vs FE       19.46
  1. Source: our elaboration on FLOS OLEI (editions 2013, 2014, and 2015)
  2. ***Means significant at 1%; **means significant at 5%; *means significant at 10%