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Utility value of management tools Advanced Herd Management Anders - - PowerPoint PPT Presentation
Utility value of management tools Advanced Herd Management Anders - - PowerPoint PPT Presentation
Utility value of management tools Advanced Herd Management Anders Ringgaard Kristensen What kind of tools? Complex systems Not just single pieces of information Management information systems Bedriftslsningen
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Why do we want to evaluate?
Farmers who consider to buy a system would like to know the expected benefit Developers who wish to sell a system would like to be able to demonstrate the benefit Only very little research has been done in this field
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Basic problems
Value of single ”pieces of information” is difficult to assess. Secondary effects
Positive: Increased focus Negative: Decreased focus in other areas
The farmer perhaps doesn’t use the system in an
- ptimal way.
Interactions production system/farmer/tool No control (what would have happened without the tool?)
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Methods (Verstegen et al. 1995)
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Methods (Verstegen et al. 1995)
Normative approaches
Decision theoretical approaches
Decision tree analysis Baysian Information Economics Control Theory
Decision analytical approaches
Simulation Linear and dynamic programming
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Methods (Verstegen et al. 1995)
Normative approaches
Decision theoretical approaches
Decision tree analysis Baysian Information Economics Control Theory
Decision analytical approaches
Simulation Linear and dynamic programming
Not value
- f tools
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Methods (Verstegen et al. 1995)
Normative approaches
Decision theoretical approaches
Decision tree analysis Baysian Information Economics Control Theory
Decision analytical approaches
Simulation Linear and dynamic programming
Not value
- f tools
Examples
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Dynamic programming
1 333 1 299 1 327 1 304 ” , DKK/(1000 kg milk) 38 59 35 50 Annual replacement % 3b 3a 2 1 9 319 9 544 9 150 9 236 Net ret., DKK/cow/year 101.3 96.4 102.7 100.0 Number of cows 25 21 28 25 Average week of replac. 6 991 7 350 6 896 7 082 Milk yield, kg/cow/year Policy
Kristensen & Thysen (1991)
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Dynamic programming
Validity
What would the farmer do without the tool? Would he/she follow the recommandations? Are the registrations correct? External validity:
Model versus real world The tool tests itself Bias for optimal policy
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Simulation (Markov chain)
Jalvingh et al. (1992)
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Simulation (Markov chain)
Validity
What would the farmer do without the tool? Would he/she follow the recommandations? Are the registrations correct? External validity:
Model versus real world The tool tests itself Bias for optimal policy
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Simulation (Monte Carlo)
Jørgensen & Kristensen (1995)
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Simulation (Monte Carlo)
Validity
What would the farmer do without the tool? Would he/she follow the recommandations? Are the registrations correct? External validity:
Model versus real world The tool does not tests itself No bias for optimal policy
The preferred normative approach
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Empirical (”positive”) approaches
Verstegen et al. (1995):
Experimental designs
Field experiments Experimental Economics
Quasi-experimental designs Nonexperimental designs
Use of data from herds
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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Designs
No control:
Only farms using the tool are included in the study
Nonequivalent control (quasi-experimental design):
A control group is included in the study afterwards As equal as possible to the farms using the tool
True control (experiment in the usual sense)
Farms are randomly divided into two groups
One group is told to use the tool The other group is not allowed to use it
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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PO: Posttest only
Not serious!
Result Time
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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NPO/TPO: Posttest only
Manipulation
Confounding between farmer type, production system and use of tool Result Time } Effect
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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PP: Pretest and posttest
Manipulation
Perhaps a general trend: All farms may have improved as those being investigated Confounding between general development and effect of tool
Result Time } Effect
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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NPP: Pretest and posttest
Correction for
General trend Confounding with farmer type (partially, no randomization)
Result Time } Effect
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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TPP: Pretest and posttest
Correction for
General trend Confounding with farmer type (randomization)
Result Time } Effect
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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TS: Time series, no control
Confounding with farmer type Development over time
Value in the beginning versus full value
Result Time
} Effect
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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NTS: Time series, control
Development over time
Value in the beginning versus full value
No confounding with farmer type
Result Time
}
Effect: b - a
a b
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Classification of designs
PO PP TS No control NPO NPP NTS Nonequivalent Control (N) TPO TPP TTS True control (N) Posttest
- nly (PO)
Pretest- posttest (PP) Time series (TS)
Verstegen et al. (1995)
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TTS: Time series, true control
Development over time
Value in the beginning versus full value
No confounding with farmer type
Result Time
}Effect
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