Stats

Front

What does the standard deviation (s) represent in a regression analysis?

Back

The typical distance of the activity level ratings from the least-squares line.

Front

What is the 20th percentile in a data set?

Back

The value below which 20% of the data falls.

Front

If a soft-drink machine discharges an average of x ounces, what does the standard deviation indicate?

Back

The variability of the fill amounts around the average.

Front

How does changing the x and y variables in a scatterplot affect the correlation?

Back

The correlation remains the same; only the interpretation of the relationship changes.

Front

What is the purpose of a least-squares regression line?

Back

To minimize the sum of the squares of the vertical distances of the points from the line.

Front

What does a higher standard deviation indicate about a data set?

Back

Greater variability or spread in the data.

Front

What is the formula for calculating the z-score?

Back

z = (X - μ) / σ, where X is the value, μ is the mean, and σ is the standard deviation.

Front

What does it mean if a distribution is normal?

Back

It is symmetric, with most of the observations clustering around the central peak.

Front

What is the significance of the 98% confidence interval in statistics?

Back

It indicates that we can be 98% confident that the true parameter lies within the interval.

Front

What is the relationship between correlation and causation?

Back

Correlation does not imply causation; two variables can be correlated without one causing the other.