When We Measure the Narrow Line Emissions of Hydrogen at 21-Cm

question 10

Multiple Choice

When we measure the narrow line emissions of hydrogen at 21-cm radio wavelength along a particular line of sight through the disk of our Galaxy,we can tell the distances to different hydrogen clouds because

• A) clouds at different distances have different Doppler shifts due to the rotation of the Galaxy.
• B) the farther away the gas cloud,the greater the delay in the arrival time of the 21-cm emission.
• C) clouds that are farther away have smaller angular sizes.
• D) the emission is weaker from clouds that are farther away.

Identify and apply proper hypothesis test procedures based on given scenarios.

Recognize the implications of Type I and Type II errors in hypothesis testing.

Determine the appropriate directionality (upper-tailed, lower-tailed, two-sided) of hypothesis tests.

Understand the relationship between sample size and margin of error in confidence intervals.

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Definitions:

Construct Validity

The extent to which a test measures the theoretical construct or concept it is intended to measure.

Content Validity

A type of validity that examines how well a test samples a universe of items.

Reliability

The extent to which a measurement instrument yields reliable and uniform outcomes across various occasions.

Validity

The degree to which a test or measurement accurately reflects the concept or construct it is intended to assess.