About this calculator
When to use this
Use 1-Var Stats any time you have one list of numbers and want to describe it: the center (mean and median), the spread (standard deviation, range, IQR), and the five-number summary. It gives the same numbers, in the same order, as the TI-84's 1-Var Stats screen.
Reading the output
- Sx vs. σx. Use Sx when your data are a sample, which is almost always. Use σx only when the list is an entire population.
- Mean vs. median. If the mean is pulled well above the median, the data are probably skewed right. For skewed data, the median is the better "typical value."
- Frequencies. If your data come in a frequency table, choose "Values + frequencies" instead of typing every repeated value. Always check that n equals the total of the frequencies.
About the quartiles
Quartiles are found the way the TI-84 does it: Q1 is the median of the lower half and Q3 is the median of the upper half, leaving out the median when n is odd. Other software may give slightly different quartiles.