Answer to Question 1
ANS: D
In quantitative research, the independent variable (intervention, treatment, or experimental variable) is manipulated or varied by the researcher to cause an effect on the dependent variable. The dependent variable (response or outcome variable) is measured to examine the effect created by the independent variable. An independent variable is a stimulus or activity that is manipulated or varied by the researcher to create an effect on the dependent variable. A dependent variable is the response behavior or outcome that the researcher wants to predict or explain. Extraneous variables exist in all studies and can affect the measurement of study variables and the relationships among them. Extraneous variables are of primary concern in quantitative studies, because they can obscure one's understanding of the relational or causal dynamics within the studies. Demographic variables are attributes of the subjects that are measured during the study and used to describe the sample.
Answer to Question 2
ANS: A
Hypotheses identify different types of relationships and numbers of variables. A well-formulated hypothesis clearly identifies the relationship between the variables. A hypothesis's value is ultimately derived from whether it can be tested in the real world. A testable hypothesis is one that contains variables that can be measured or manipulated in the world.
Experimental evidence of the effect of allelochemicals on plant production.
Extent of agricultural activity across the planet (data from Foley et al. 2005).
Frequency coding in the nervous system: Threshold stimulus.
The First-Pass Effect
Perception Activity
Classical-Conditioning Activity