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Quantitative
Methods
for
Lawyers Research Design - Part IV
Class #4
@ computational
computationallegalstudies.com
professo...
In our last session, we were
discussing randomized control trials
Randomized Control Trial
Control Group
Treatment Group
Follow Up Evaluation
Follow Up Evaluation
RCT’s Are Often Considered the
Gold Standard in Science
Because if properly executed
there is a fairly clean relationship
between cause and effect
Randomized Control Trial
Control Group
Treatment Group
Follow Up Evaluation
Follow Up Evaluation
Lets go through RCT’s and
related forms of experiments
Experimental Data
Experiments are a great way to
attempt to isolate causal effects
Major Weakness is External Validity (due to
unknown interactions between variables, etc.)
Key Ideas:
Random Assignment
Representativeness
Experimental Control
Experimental Manipulation
Factorial Design
Double Bli...
Random Assignment
P r o b a b i l i t y o f B e i n g i n
Treatment or Control Group
Should Be Equal
Composition of the Tr...
Would like to overall subject
group to mirror the population
of interest
Example: If we are interested in
studying juvenil...
Experimental Control
Classic Example is Medical Trial Involving a New Drug
Experimental Group
Given the New Drug
Control G...
Experimental Manipulation
Under Ideal Conditions this would be the only
difference between treatment and control group
Exp...
Variables
Concept: A variable is an attribute which
describes a part of the makeup of an individual.

Examples are gender, age, empl...
Studies are usually designed to collect and
then compute the distribution and variation
between and among the variables.
It should be noted that a variable, by
definition, must possess variation; if all of the
studied population have the same a...
There are different types of variables.
One important division is between
independent variables and
dependent variables.

Independent variables act as the
potential cause. They influence or
predict an outcome from the dependent
variable. They ar...
Dependent variables act as the effect
(or potential effect). They may
change because of the influence of the
independent va...
Other Types
of Variables
Categorical variables can take on
one of a limited, and usually fixed,
number of possible values
Nominal variables are variables that have
two or more categories but which do not
have an intrinsic order. For example, a ...
Dichotomous variables are nominal variables
which have only two categories or levels. For
example, we could categorize som...
Ordinal variables are variables that have two
or more categories just like nominal variables
only the categories can also ...
Describe some variables could
that could predict/determine
the price of a house?
How Are They Coded?
School Quality
New or Used
Pool
Garage
Distance from City Center
... etc.
BedRooms
BathRooms
Square Feet
Lot Size
Age of H...
Bias in
Scientific Study
Please note that “bias” in research terms is
different.
In normal language, bias is a prejudicial look at
someone or somet...
What is a Correlation?
What is a Correlation?
Causality
Sometimes the statistical test shows a clear and
significant relationship called a correlation between
two variables. 



T...
Daniel Martin Katz
@ computational
computationallegalstudies.com
lexpredict.com
danielmartinkatz.com
illinois tech - chica...
Quantitative Methods for Lawyers - Class #4 - Research Design Part IV - Professor Daniel Martin Katz
Quantitative Methods for Lawyers - Class #4 - Research Design Part IV - Professor Daniel Martin Katz
Quantitative Methods for Lawyers - Class #4 - Research Design Part IV - Professor Daniel Martin Katz
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Quantitative Methods for Lawyers - Class #4 - Research Design Part IV - Professor Daniel Martin Katz

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Quantitative Methods for Lawyers - Class #4 - Research Design Part IV - Professor Daniel Martin Katz

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Quantitative Methods for Lawyers - Class #4 - Research Design Part IV - Professor Daniel Martin Katz

  1. 1. Quantitative Methods for Lawyers Research Design - Part IV Class #4 @ computational computationallegalstudies.com professor daniel martin katz danielmartinkatz.com lexpredict.com slideshare.net/DanielKatz
  2. 2. In our last session, we were discussing randomized control trials
  3. 3. Randomized Control Trial Control Group Treatment Group Follow Up Evaluation Follow Up Evaluation
  4. 4. RCT’s Are Often Considered the Gold Standard in Science
  5. 5. Because if properly executed there is a fairly clean relationship between cause and effect
  6. 6. Randomized Control Trial Control Group Treatment Group Follow Up Evaluation Follow Up Evaluation
  7. 7. Lets go through RCT’s and related forms of experiments
  8. 8. Experimental Data
  9. 9. Experiments are a great way to attempt to isolate causal effects
  10. 10. Major Weakness is External Validity (due to unknown interactions between variables, etc.)
  11. 11. Key Ideas: Random Assignment Representativeness Experimental Control Experimental Manipulation Factorial Design Double Blind
  12. 12. Random Assignment P r o b a b i l i t y o f B e i n g i n Treatment or Control Group Should Be Equal Composition of the Treatment or Control Group Should Be Similar Under Ideal Conditions this Eliminates other Confounds that could undermine Validity
  13. 13. Would like to overall subject group to mirror the population of interest Example: If we are interested in studying juveniles than the composition of bot h our treatment and control groups should be juveniles Representativeness
  14. 14. Experimental Control Classic Example is Medical Trial Involving a New Drug Experimental Group Given the New Drug Control Group Given the Sugar Pill How would Double Blind work in this context? What is a Placebo Effect?
  15. 15. Experimental Manipulation Under Ideal Conditions this would be the only difference between treatment and control group Experimental Manipulation and Factorial Design Watch out for too many Manipulations at one time
  16. 16. Variables
  17. 17. Concept: A variable is an attribute which describes a part of the makeup of an individual.
 Examples are gender, age, employment status, income level, race, or education level.
  18. 18. Studies are usually designed to collect and then compute the distribution and variation between and among the variables.
  19. 19. It should be noted that a variable, by definition, must possess variation; if all of the studied population have the same attribute, for example they are all employed, that attribute is a constant rather than a variable. 

  20. 20. There are different types of variables. One important division is between independent variables and dependent variables.

  21. 21. Independent variables act as the potential cause. They influence or predict an outcome from the dependent variable. They are the X’s on the right side of the equation.

  22. 22. Dependent variables act as the effect (or potential effect). They may change because of the influence of the independent variable. This is the Y on the left hand side of the equation.
  23. 23. Other Types of Variables
  24. 24. Categorical variables can take on one of a limited, and usually fixed, number of possible values
  25. 25. Nominal variables are variables that have two or more categories but which do not have an intrinsic order. For example, a real estate agent could classify their types of property into distinct categories such as houses, condos, co-ops or bungalows.
  26. 26. Dichotomous variables are nominal variables which have only two categories or levels. For example, we could categorize somebody as either Treated or Not Treated as either "Yes" or “No”. In the real estate agent example, if type of property had been classified as either residential or commercial then "type of property" would be a dichotomous variable.
  27. 27. Ordinal variables are variables that have two or more categories just like nominal variables only the categories can also be ordered or ranked. Large, Medium, Small, etc.
  28. 28. Describe some variables could that could predict/determine the price of a house? How Are They Coded?
  29. 29. School Quality New or Used Pool Garage Distance from City Center ... etc. BedRooms BathRooms Square Feet Lot Size Age of House Crime Rate
  30. 30. Bias in Scientific Study
  31. 31. Please note that “bias” in research terms is different. In normal language, bias is a prejudicial look at someone or something. 
 
 In research, bias is an action or inaction which can skew the outcome. 
 
 It does not have to be intentionally done. Bias in Scientific Study
  32. 32. What is a Correlation?
  33. 33. What is a Correlation?
  34. 34. Causality
  35. 35. Sometimes the statistical test shows a clear and significant relationship called a correlation between two variables. 
 
 There is a tendency to then conclude that the correlation shows causation. It may (or may not). 
 It could have nothing to do with causation or it could only have an indirect affect on the causation.
  36. 36. Daniel Martin Katz @ computational computationallegalstudies.com lexpredict.com danielmartinkatz.com illinois tech - chicago kent college of law@

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