Causality 

   The primary goal of science is to establish a cause and effect relationships

     A causes B to...

         A is the independent variable

            the variable being manipulated to hopefully result in a cause and effect relationship with the dependent variable

         B is the dependent variable 

            the variable being tested to see the effect of the independent variable

   The establish causality an experiment is needed

 

   The Experiment 

      Control over A ( the independent variable ) 

         We get control by creating different groups to compare against each other

            Typically an experimental group and a control group

                 both groups are treated the same except one has the independent variable that is manipulated 

      Control over confounding variables

         We get control over the variables that can interfere with the experiment causing false results by random assignment 

      We measure the dependent/outcome variable of every subject

   

   Random Assignment as a control for A

      To control for the independent variable by way of random assignment, we make sure the groups are equal to each other prior to the       treatment. 

         this allows the researcher to attribute any change to the manipulation of the independent variable

 

 Meanings of control 

      control over Independent variable

      control over the environment 

      Any other attempt made to eliminate the influence of a threat to a casual inference 

 

  Problems with experiments 

      Can't be used to answer every question

      Are not natural

      Unable to control for everything 

      

   Options other than a tradition experiment 

      quasi-experiment

         no control over independent variable 

      Correlational study 

         only looks at the relationship between variables 

         no cause and effect relationip ( causality ) 

 

The importance of this is for Validity 

     Validity equals to the accuracy of the experiment or study

         determines whether the question you asked was correct or not 

      Two main types: 

         Internal validity : the degree to which the results are attributed to the independent variable and not some other rival explantion

         External validity : the extent to which the results are generalizable