Step 1: Understand the concept of screening effect.
The screening effect refers to the ability of inner electrons to shield outer electrons from the attractive force of the nucleus.
Step 2: Conclusion.
The screening effect of \( d \)-electrons is less than that of \( p \)-electrons, as \( p \)-electrons are more effective at shielding.
Final Answer:
\[
\boxed{\text{Less than } p\text{-electrons}}
\]