Ch 1 A part of moving causal theories into scientific knowledge is to think about the world in terms of models in which the concepts of interest become variables that are causally linked together by theories Variable an element feature or factor that is liable to vary or change Variables definable quantities that can take on at least two values big versus small etc A theory is a tentative conjecture about the causes of some phenomenon of interest which develops causal theories Example the promise of rebel biased intervention by strong third parties causes civil wars to occur More common formula on an increase in the likelihood of rebel biased intervention by strong third parties causes an increase in the probability of civil war onset The first step in testing a particular theory is to restate it is one or more testable hypotheses A hypothesis is a theory based statement about a relationship we expect to observe For every hypothesis there is a corresponding null hypothesis A null hypothesis is also a theory based statement but it is about what we would observe if there were no relationship between an independent variable and the dependent variable Hypothesis testing is a process in which scientists evaluate systematically collected evidence to make a judgment of whether the evidence favors their hypothesis of favors the corresponding null hypothesis Ex Hypothesis testing If relatively few civil wars start when strong states are likely to help the rebels then our hypothesis wouldn t have very much support Causal Theory Hypothesis In scientific method the word empirical refers to the use of working hypothesis that can be tested using observation and experiment Empirical data is produced by experiment and observation Based on real world observation Empirical Testing theory We evaluate our hypotheses relative to the null hypotheses Next from the results of our hypothesis tests we evaluate our causal Evaluation of Hypothesis A consider new evidence theory is never proven because scientists are always willing to Evaluation of Causal Theory Scientific Knowledge scientists will still favor the null hypothesis The process of hypothesis testing reflects how hard scientists are on their own theories As scientists evaluate systematically collected evidence to make a judgment of whether the evidence favors their hypothesis or favors the corresponding null hypothesis they always favor the null hypothesis Even when the hypothesis has an 80 20 edge over the null hypothesis most Scientific fields go through cycles of accumulating knowledge based on a set of shared assumptions and commonly accepted theories about the way that the world works Together these assumptions and accepted theories from a paradigm Once a paradigm is widely accepted scientists can pursue increasingly technical questions based off that paradigm Paradigm A set of assumptions concepts values and practices that constitutes a way of viewing reality fo r the community that shares them The state of research under an accepted paradigm is referred to as normal science Sometimes new theories or new evidence come to light which can help inspire a paradigm shift Ex The Earth previously thought as center of the universe Newton s theory of gravity did not work at high speeds Einstein modified it Voting behavior thought as influenced from campaigning ads evidence proved voting behavior is consistent even before campaigning Variables should be thought in terms of label and its values The variable label is a description of what the variable is and the variable values are the denominations in which the variable occurs Ex the variables that reflect individual s age Label age Value years or months hours even minutes We operationalize our variables into something we can actually measure e g how do you measure a state s wealth or level of democracy The incumbent president will fare better when the economy is relatively healthy The state of the economy is the independent variable and the outcome of the elections is the dependent variable The value of the dependent variable depends on the value of the independent variable Change in independent CAUSES change in dependent Relationships can be 1 Positive higher GDP causes higher Polity score upward slope 2 Negative higher causes lower Polity score downward slope Thus a theory is a conjecture that the independent variable is causally related to the dependent variable Change in the value of the independent variable CAUSES change in the value of the dependent variable One way to initially evaluate a particular theory is to think about the causal explanation behind it The causal explanation behind a theory is the answer to the question why do you think that this independent variable is causally related to this dependent variable Ex The state of the economy is causally related to the outcome of presidential elections because voters hold the president responsible for management of the national economy A theoretical model is the combination of independent variables the dependent variable and the causal relationships that are theorized to exist among them Models are simplifications usually not accurate They are most useful to us when they are inaccurate than when they are accurate Ex maps In models it is important to strike a balance between complexity generality and parsimony statistical accuracy Lots of variables in the world covary or have nontrivial correlation Covary covariation when two variables vary together The term covariation is used to describe circumstances in which two variables vary A and B covary when we observe higher values of A we generally also observe higher values of variable B It also applies when we observe higher values of A we also observe lower values of B But also remember CORRRELATION COVARIATION IS NOT CAUSATION Ex ice cream sales and murder rates go up thus ice cream causes murder Illogical Rules of the road 1 Theories should be causal 2 Don t let data alone drive theories 3 Consider only empirical evidence 4 Avoid normative statements statements about how the world ought to be ex There should be no poverty 5 Pursue both generality and parsimony theories that are applicable to a lot and simple to understand although often there are trade offs between the two Ch 2 The unit of analysis is the major entity that is being analyzed in a study It is the what or who that is being studied In social science research typical units of analysis include individuals most common groups
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