Statistical Studies, Vocabulary, Empirical Rule, and Z-Score

Front

What is the shape of the data when it is skewed left?

Back

The tail on the left side of the distribution is longer or fatter than the right side.

Front

What is the empirical rule in statistics?

Back

The empirical rule states that for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, 95% within two standard deviations, and 99.7% within three standard deviations.

Front

What is a Z-score?

Back

A Z-score indicates how many standard deviations an element is from the mean. It is calculated as (X - μ) / σ.

Front

What percentage of scores are less than the mean in a normal distribution?

Back

50% of scores are less than the mean in a normal distribution.

Front

If the mean is 70 and the standard deviation is 5, what is the Z-score for a score of 75?

Back

Z = (75 - 70) / 5 = 1.

Front

What does a Z-score of -2 indicate?

Back

A Z-score of -2 indicates that the value is 2 standard deviations below the mean.

Front

What is the mean in a normal distribution?

Back

The mean is the average of all data points and is the center of the normal distribution.

Front

What is the standard deviation in statistics?

Back

The standard deviation measures the amount of variation or dispersion in a set of values.

Front

What percentage of data falls between the mean and one standard deviation above the mean in a normal distribution?

Back

34% of the data falls between the mean and one standard deviation above the mean.

Front

What is a biased study?

Back

A biased study is one that does not accurately represent the population being studied, often due to the method of data collection.