Z Score and Percentile

Front

What is a Z Score?

Back

A Z Score is a statistical measurement that describes a value's relationship to the mean of a group of values, expressed in terms of standard deviations from the mean.

Front

How do you calculate a Z Score?

Back

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

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 of the following data set: 70, 96, 74, 87, 89, 82, 80, 90, 81, 91, 95, 68?

Back

The mean is 83.58.

Front

If a student scores at the 55th percentile, what does this mean?

Back

It means that 55% of the class scored the same or worse than the student.

Front

What is a percentile?

Back

A percentile is a measure used in statistics indicating the value below which a given percentage of observations in a group of observations falls.

Front

How do you find the percentile rank of a value in a data set?

Back

Percentile Rank = (Number of values below X / Total number of values) * 100.

Front

What is the standard deviation?

Back

Standard deviation is a measure of the amount of variation or dispersion in a set of values.

Front

What does a Z Score of 0 represent?

Back

A Z Score of 0 indicates that the value is exactly at the mean.

Front

If the mean height of 3rd graders is 52 inches and a student is 47 inches tall, what is their Z Score?

Back

The Z Score is -2.