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Increasing Statistical Power
If a research design lacks adequate statistical power, researchers can increase it by either increasing the sample size or strengthening the relationship. Strengthening the relationship can be achieved by using a stronger experimental manipulation or by carefully controlling extraneous variables to reduce data noise, such as employing a within-subjects design instead of a between-subjects design. However, the most common and practical strategy to boost power is simply to increase the sample size.
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Research Methods in Psychology - 4th American Edition @ KPU
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Type II Error
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Relationship Between Statistical Power and Relationship Strength
Which of the following best defines the statistical power of a research design?
A researcher designs a study with a statistical power of .80. This means there is a 20% probability that the study will fail to detect a real effect that actually exists in the population.
A researcher is refining their study design to improve the probability of detecting a real relationship between variables. Match each design decision with its specific impact on the study's statistical power.
A researcher is designing a study to examine how social media use affects attention span. Arrange these four study configurations in order from the lowest statistical power (at the top) to the highest statistical power (at the bottom) by analyzing how their parameters influence the probability of detecting a real relationship.
A researcher is developing a study to detect a subtle relationship between sleep duration and cognitive performance (). With a fixed budget that limits the sample size to participants, which of the following research plans correctly synthesizes the necessary design elements to maximize statistical power?
Example of Sample Size Requirements for High Statistical Power
Assuming a real effect exists in the population, arrange the following study designs in order based on their probability of failing to detect that effect (Type II error), from the highest risk of error (at the top) to the lowest risk of error (at the bottom).
A researcher is evaluating two proposed study designs for a clinical trial. Design A has a reported statistical power of , while Design B is estimated to have a probability of failing to detect a real effect that exists in the population. To ensure the highest probability of correctly identifying a relationship, the researcher should select the design with a power of _____.
Match each term related to statistical power with its correct description.
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A research team is reviewing three studies that each suffer from low statistical power. Match each study's situation with the most appropriate strategy for increasing its statistical power.
A researcher is investigating whether listening to classical music while studying improves test scores. In a pilot study, he compared two separate groups of 10 students and found a non-significant result. For his main study, he decides to switch to a within-subjects design, where every student completes one test while listening to music and another test in silence, in order to control for individual differences in student ability.
A researcher finds their study lacks sufficient statistical power to detect a predicted effect. Sequence the following adjustments based on the underlying mechanism they use to boost power, starting with the strategy that reduces unsystematic variability (noise), followed by the one that increases the magnitude of the relationship, and ending with the most common practical method.
A researcher evaluates their underpowered study and concludes that because they cannot increase their sample size, they have no other scientifically valid options for increasing the study's statistical power.
If a research design lacks adequate statistical power, what are the two general ways a researcher can increase it?
A researcher who is unable to increase their sample size can still boost their study's statistical power by strengthening the relationship between variables, which can be achieved through a stronger experimental manipulation or by controlling extraneous variables.
When a research design lacks adequate statistical power, the most common and practical strategy researchers use to boost it is to increase the _____.
A research team wants to optimize the statistical power of their upcoming experiments. Match each researcher's scenario with the specific strategy they are applying to increase statistical power.
A psychology researcher realizes that their between-subjects study lacks adequate statistical power. Without recruiting additional participants, they decide to transition to a within-subjects design to control extraneous variables. By doing so, the researcher is attempting to increase power by strengthening the relationship through the reduction of data _____.
Evaluate the following strategies for addressing an underpowered research design. Sequence the strategies starting with the most common and practical option, followed by the relationship-strengthening option that reduces noise, and ending with the relationship-strengthening option that modifies the independent variable.