Which of the following evidence is particularly difficult to obtain when one is trying to determine efficient causality based on relational research?
A) Temporal Sequence: Establishing the precise sequence of events in a relational research setting can be challenging, making it difficult to determine efficient causality.
B) Control Variables: Identifying and controlling for all relevant variables that could influence the relationship between the variables of interest is often complex in relational research.
C) External Validity: Ensuring that the findings from relational research can be generalized to other populations or settings is a significant challenge, affecting the ability to establish efficient causality.
D) Measurement Accuracy: Obtaining accurate and reliable measurements of the variables involved in the relationship is crucial but can be difficult to achieve in relational research settings.