What are two methods scientist use to obtain empirical evidence

The two methods scientists use to obtain empirical or evidential data is through:
  
1. Experimentation. This will majorly utilized in the various fields of science, hence this uses the variables of determining the independent and dependent variables –causation and effect of one or two variables to one another and vice versa. This is widely done in laboratories but natural observations is also one condition.  

2.    Descriptive. This is one method of gathering data by using tests, interview and assessment, also to correlate the study. Moreover, this is the methods which is widely used in social sciences. Note that questionnaires aren’t the only methods in gathering data as mentioned by the above respondent, many authors would argue and support this claim.   

The hawk receives 0.1% energy from the caterpillar although the caterpillar gets eaten by another bird smaller than the hawk first

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