statistics Vocabulary
JamWise Education TeamยทUpdated March 2026
The statistics strand is a core part of the K-8 math curriculum. It encompasses 44 vocabulary terms that students encounter as they progress from kindergarten through 8th grade. Each term builds on previous knowledge, creating a spiral of deepening understanding that prepares learners for increasingly complex concepts.
Understanding statistics vocabulary is essential for classroom discussions, assessments, and real-world application. Below you will find every term organized by grade level, so teachers and parents can quickly identify which words are appropriate for their students and explore definitions tailored to each developmental stage.
6th Grade
(18 terms)
Average
Another name for the mean. To find the average, add all the values in a data set and divide by the number of values.
Box plot
A graph that shows the spread of a data set using five key values: minimum, first quartile, median, third quartile, and maximum.
Categorical data
Data where the values are categories or labels rather than numbers. Favorite color, type of pet, and brand of shoe are examples of categorical data.
Distribution
The way data values are spread out. A distribution shows how often each value occurs in a data set.
Dot plot
A graph that shows data as dots stacked above values on a number line. Each dot represents one data point.
Frequency
The number of times a particular value shows up in a data set. If the score 85 appears 4 times, its frequency is 4.
Histogram
A bar graph that groups data into ranges (bins) and shows how many values fall in each range. The bars touch each other because the ranges are connected.
Interquartile range
The IQR measures how spread out the middle half of a data set is. It is the difference between the third quartile (Q3) and the first quartile (Q1).
Mean
The average of a set of numbers. Add all the values and divide by how many values there are. The mean of 2, 4, and 6 is 4.
Mean absolute deviation
The MAD measures how spread out values are from the mean. You find the distance of each data point from the mean, then average those distances.
Measure of center
A single number that represents a typical value in a data set. The mean and median are both measures of center.
Median
The middle value in a data set when the numbers are arranged in order. If there is an even number of values, the median is the average of the two middle values.
Mode
The value that appears most often in a data set. A data set can have one mode, more than one mode, or no mode at all.
Numerical data
Data made up of numbers that represent quantities. Heights, weights, and test scores are examples of numerical data.
Quartile
One of three values (Q1, Q2, Q3) that divide an ordered data set into four equal groups. Q2 is the same as the median.
Range
The difference between the largest and smallest values in a data set. If scores go from 65 to 95, the range is 30.
Statistical question
A question that you expect to get different answers from different people or situations. 'How tall are the students in our class?' is statistical because heights vary.
Variability
The tendency of data values to differ from each other. High variability means the data is spread out; low variability means the data is clustered together.
7th Grade
(19 terms)
Biased sample
A sample that does not fairly represent the whole population because of how it was chosen. Asking only athletes about favorite sports is biased.
Chance experiment
An activity you can repeat where you do not know what will happen each time. Rolling a die and flipping a coin are chance experiments.
Compound event
An event made up of two or more simple events happening together. Flipping a coin AND rolling a die is a compound event.
Event
An outcome or set of outcomes from a chance experiment. Rolling an even number on a die is an event that includes outcomes 2, 4, and 6.
Experimental probability
The probability of an event based on actual experiments or observations. It equals the number of times the event happened divided by the total number of trials.
Inference
A conclusion you draw about a population based on data from a sample. If 60% of a sample prefers pizza, you infer about 60% of the whole group does too.
Interquartile range
The IQR is the difference between the third quartile and the first quartile. It measures the spread of the middle 50% of the data.
Mean
The average of a data set, found by adding all values and dividing by the number of values. Also called the arithmetic mean.
Mean absolute deviation
The MAD is the average distance between each data point and the mean. It tells you how spread out the data is from the center.
Median
The middle value of an ordered data set. If there are two middle values, the median is their average.
Outcome
A possible result of a chance experiment. When you roll a die, the outcomes are 1, 2, 3, 4, 5, and 6.
Population
The entire group you want to study or collect data about. If you want to know the favorite lunch of all 6th graders, the population is all 6th graders.
Probability
A number between 0 and 1 that describes how likely an event is to happen. 0 means impossible and 1 means certain.
Random sampling
A method of choosing a sample where every member of the population has an equal chance of being selected.
Representative sample
A sample that accurately reflects the characteristics of the entire population. It should be chosen randomly to avoid bias.
Sample
A smaller group chosen from the population to represent it. A good sample is random and representative of the whole population.
Sample space
The set of all possible outcomes of an experiment. For a coin flip, the sample space is {heads, tails}.
Simulation
A model used to imitate a real-world situation and study probability. You might use a random number generator to simulate rolling a die.
Theoretical probability
The probability of an event based on reasoning about equally likely outcomes. The theoretical probability of rolling a 3 on a fair die is 1/6.
8th Grade
(11 terms)
Cluster
A group of data points on a scatter plot that are close together, suggesting a concentration of data in that area.
Line of best fit
A straight line drawn through a scatter plot that comes closest to the data points. It shows the general trend of the data.
Linear association
A relationship between two variables where the data points cluster around a straight line on a scatter plot.
Negative association
A pattern in a scatter plot where one variable tends to increase while the other decreases.
No association
When the data points in a scatter plot show no clear pattern or trend between the two variables.
Nonlinear association
A relationship between two variables where the data points cluster around a curve rather than a straight line on a scatter plot.
Outlier
A data point that is much smaller or larger than most of the other data values. It stands far away from the main pattern.
Positive association
A pattern in a scatter plot where both variables tend to increase together. As one goes up, the other goes up too.
Relative frequency
A frequency divided by the total number of data points, often expressed as a percentage. It shows the proportion of the data in each category.
Scatter plot
A graph that shows pairs of data as dots on a coordinate plane to reveal relationships or patterns between two variables.
Two-way frequency table
A table that shows the frequency of data for two different categories at once. Rows represent one category and columns represent another.