जब एक प्रयोगात्मक डिजाइन में स्वतंत्र चरों की संख्या बढ़ाई जाती है, तो कुल भिन्नता (टोटल वेरिएंस) के उपचार (ट्रीटमेंट) और त्रुटि (एरर) घटकों में क्या परिवर्तन देखे जाते हैं?

Given below are two statements: Statement I: An operational definition translates a vague construct into measurable and observable terms for the purpose of a specific research study. Statement II: A moderator variable is a type of extraneous variable that the researcher fails to control, thereby providing an alternative explanation for the results. In the light of the above statements, choose the correct answer from the options given below:

The variable manipulated by the experimenter in an experiment is called the ________ variable.