Why is it important for a researcher to ensure that a measurement instrument used during data collection is both reliable and valid?

A researcher uses a measurement instrument that produces inconsistent results when measuring the same phenomenon under similar conditions. Analyse THREE potential implications of using this unreliable instrument in the research study. For each implication, explain how the unreliability could affect the quality, interpretation, or validity of the research findings.           

Using the PTA data:15, 20, 25, 30, 20, 35, 40, 25, 20, 30, 45, 25, 20, 35, 50, 30, 25, 20, 40, 30calculate:  The Mean                                 

Using the PTA data:15, 20, 25, 30, 20, 35, 40, 25, 20, 30, 45, 25, 20, 35, 50, 30, 25, 20, 40, 30calculate: Median

Analyze the test scores dataset: 64,77,78,82,89,92,95. What would be the calculated range of the scores?

A clinician measures dysphagia quality-of-life scores (non-normally distributed continuous data) in a single cohort before and after an intensive swallowing therapy program. Which statistical test is most appropriate?

Which statement best defines biostatistics?

Using the PTA data:15, 20, 25, 30, 20, 35, 40, 25, 20, 30, 45, 25, 20, 35, 50, 30, 25, 20, 40, 30calculate:  Range

A researcher wants to ensure that participants are selected fairly and that no particular group is unfairly excluded or exploited. Which ethical principle is most directly involved?

Which statement about a p-value is most accurate?