Statistics ČZU

Arithmetic mean

Sum of all observed values, divided by the total count of observations.

Median

Middle observation after the data has been arranged in ascending or descending order.

Mode

Category or value that occurs most frequently in a dataset.

Sample variance

The average squared deviation of the observations from the sample mean

Standard deviation

Typical distance of observations from the mean. Basically square root of sample deviation.

Coefficient of variation

Variability relative to the mean. Measures how large the standard deviation is compared with the mean.

Quartiles

Instead of considering only the min and max values of a range, we identify values that separate the data into four approximately equal groups. These values are called quartiles.

Interquartile range (IQR)

Measures how widely the middle 50% (Q2 and Q3) are spread. Unlike range, ignores low 25% and high 25% of the data. Less sensitive to extreme observations

Arithmetic Mean: Uses all observations

Yes

Median: Uses all observations

No

Arithmetic Mean: Affected by extreme observations

Strongly

Median: Affected by extreme observations

Very little

Arithmetic Mean: Requires ordered data

No

Median: Requires ordered data

Yes

Arithmetic Mean: May not be an observed value

Yes

Median: May not be an observed value

Yes

Arithmetic Mean: Suitable for symmetric distributions

Excellent

Median: Suitable for symmetric distributions

Excellent

Arithmetic Mean: Suitable for skewed distributions

Sometimes misleading

Median: Suitable for skewed distributions

Usually preferred