What does spatial dependence imply about observations that are geographically close?

• A. They are likely to be dissimilar
• B. They are unrelated
• C. They are more likely to be similar
• D. They are always identical

Answer: (C)

Spatial dependence means observations that are geographically close tend to resemble each other because nearby locations share similar environmental factors, processes, or exposures. This creates positive spatial autocorrelation, so values at nearby sites are more likely to be similar than those farther apart. It’s not that they are always identical, but proximity increases the chance of similarity. The other options imply no relation, dissimilarity, or perfect equality, which contradicts the idea of a gradual spatial structure where nearby values tend to cluster together.