fish: fish

fishR Documentation



Wooldridge Source: K Graddy (1995), “Testing for Imperfect Competition at the Fulton Fish Market,” RAND Journal of Economics 26, 75-92. Professor Graddy's collaborator on a later paper, Professor Joshua Angrist at MIT, kindly provided me with these data. Data loads lazily.




A data.frame with 97 observations on 20 variables:

  • prca: price for Asian buyers

  • prcw: price for white buyers

  • qtya: quantity sold to Asians

  • qtyw: quantity sold to whites

  • mon: =1 if Monday

  • tues: =1 if Tuesday

  • wed: =1 if Wednesday

  • thurs: =1 if Thursday

  • speed2: min past 2 days wind speeds

  • wave2: avg max last 2 days wave height

  • speed3: 3 day lagged max windspeed

  • wave3: avg max wave hghts of 3 & 4 day lagged hghts

  • avgprc: ((prca*qtya) + (prcw*qtyw))/(qtya + qtyw)

  • totqty: qtya + qtyw

  • lavgprc: log(avgprc)

  • ltotqty: log(totqty)

  • t: time trend

  • lavgp_1: lavgprc[_n-1]

  • gavgprc: lavgprc - lavgp_1

  • gavgp_1: gavgprc[_n-1]


This is a nice example of how to go about finding exogenous variables to use as instrumental variables. Often, weather conditions can be assumed to affect supply while having a negligible effect on demand. If so, the weather variables are valid instrumental variables for price in the demand equation. It is a simple matter to test whether prices vary with weather conditions by estimating the reduced form for price.

Used in Text: pages 443, 580




wooldridge documentation built on May 3, 2023, 5:06 p.m.