Fish Stock Data - Excel

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Fish Stock Data - Excel Powered By Docstoc
					                              Data for Stratified Sampling Problem
                  The data are the basket weights and numbers of fish sampled.
           Stratum                             Big Fish      Med. Fish     Small Fish
      Total No. Baskets                           31            47             28
     No. Baskets Sampled                          10            10             10
                                           Weight No.Fish Weight No.Fish Weight No.Fish
         The Sample Data                    77.3        9  82.8      19   39.3      35
                                           125.6       14  29.9      17   86.5      40
                                           114.4       13  31.2      19  181.9      44
                                           162.2       18  73.8      15   59.6      31
                                            65.1        8  86.8      20   86.6      44
                                            41.9        5 266.4      24   31.0      25
                                           154.1       20  93.8      23   96.3      42
                                           104.9       13  67.6      21   60.6      39
                                            79.7       10 129.1      18   88.8      34
                                            91.0       13 256.6      21  101.5      27
    (1) Estimate the average weight of a basket of fish.
    (2) Estimate the total weight of all the baskets of fish.
    (3) Estimate the average weight of a fish.
    (4) Estimate the total number of fish in the market.
    (5) Suggest a better way to sample for the average basket weight.

c5616182-1550-43bf-aa16-3b6d79233a7c.xls          Stratified Sampling                4/19/2011
You are preparing to do a stock assessment and have collected samples of fish
from the two major ports that exploit a certain fish stock. Some of the data
available to you are sample tallies by port of the number of immature and mature
fish by size class (below).

   (a)    Using a least-squares approach, fit logistic curves to each of the two


          Prop_Mature( Len ) = 1 / { 1+ exp[ -B * ( Len - L50 ) ] }

   (b)    Repeat (a) but this time using a weighted least-squares approach. The
          weights for each (Prop_Mature,Len) data pair should be inversely
          proportional to the variance of the Prop_Mature.

   (c)    For the stock assessment you need a single maturity versus length
          curve. Discuss how you might derive this curve from the information
          available to you. Discuss what additional information you might be able
          to acquire and how you would use it for deriving a "combined" curve.

                           North Port               South Port
             Length        N Mature        N Immat. N Mature N Immat.
               10                                       0       20
               12                                       1       19
               14                                       1       19
               16                                       1       19
               18                                       4       16
               20                                       2       18
               22              4              16        6       14
               24              3              17        9       11
               26              11              9       10       10
               28              9              11       13        7
               30              9              11
               32              18              2
               34              17              3
               36              18              2
               38              17              3
               40              20              0



                                    Length-Maturity Relationship
c5616182-1550-43bf-aa16-3b6d79233a7c.xls                                     4/19/2011
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                                                Length-Maturity Relationship
            c5616182-1550-43bf-aa16-3b6d79233a7c.xls                           4/19/2011

				
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