Glossary
Axes labels (graph component)
Text descriptions on the horizontal (x-axis) and vertical (y-axis) of a graph that indicate what each axis represents and its units.
Example:
Misinterpreting the axes labels, such as confusing 'years' with 'months', can lead to incorrect conclusions from a graph.
Bar graphs
Graphs that use rectangular bars of varying heights or lengths to compare discrete categories or groups of data.
Example:
A bar graph could effectively compare the number of students who prefer different subjects like Math, Science, or English.
Box plots
Graphical displays that summarize the distribution of a dataset using five key values: minimum, first quartile (Q1), median, third quartile (Q3), and maximum.
Example:
A box plot can quickly show the spread and central tendency of a class's test scores, highlighting any potential outliers.
Correlation vs. Causation
Correlation indicates that two variables move together, while causation means one variable directly causes a change in the other; correlation does not imply causation.
Example:
Observing that ice cream sales and drowning incidents both increase in summer shows correlation, but ice cream doesn't cause drowning; the underlying cause is hot weather.
Data points (graph component)
Individual pieces of information plotted on a graph, representing specific measurements or observations.
Example:
Each data point on a scatterplot might represent a student's height and weight.
Footnotes (graph component)
Additional notes or explanations placed at the bottom of a graph, providing context, sources, or important details about the data.
Example:
A footnote might clarify that the data presented in the graph only includes participants from a specific age group.
Histograms
Graphs that display the frequency distribution of a continuous dataset, using bars to represent data within specific numerical ranges or bins.
Example:
A teacher might use a histogram to show the distribution of scores on a recent exam, grouping scores into ranges like 70-79, 80-89, etc.
Interquartile range (IQR)
A measure of statistical dispersion, calculated as the difference between the third quartile (Q3) and the first quartile (Q1), representing the middle 50% of the data.
Example:
The interquartile range is useful for understanding the spread of the central part of the data, less affected by extreme values.
Legend (graph component)
A key or guide on a graph that explains the meaning of different colors, symbols, or line styles used to represent various data series.
Example:
If a graph shows multiple lines, the legend will tell you which line represents 'Group A' and which represents 'Group B'.
Line graphs
Graphs that display data points connected by lines, primarily used to show trends or changes in data over a continuous period, such as time.
Example:
To visualize how a student's test scores improved throughout the semester, a line graph would clearly show the upward trend.
Mean
The average of a dataset, calculated by summing all values and dividing by the total number of values.
Example:
To find the mean score of a class, you add up all the students' scores and divide by the number of students.
Median
The middle value in a dataset when the values are arranged in numerical order.
Example:
In the dataset {2, 5, 8, 10, 12}, the median is 8, as it's the central value.
Mode
The value that appears most frequently in a dataset.
Example:
In a list of favorite colors, if 'blue' is chosen by the most people, then 'blue' is the mode.
Negative correlation
A relationship between two variables where one tends to increase as the other decreases.
Example:
You might observe a negative correlation between the number of hours spent watching TV and academic performance.
No correlation
A situation where there is no discernible relationship or pattern between two variables.
Example:
There is typically no correlation between a person's favorite color and their height.
Outliers
Data points that are significantly different from other observations in a dataset, potentially skewing statistical measures.
Example:
If most students score between 70-90 on a test, but one student scores 20, that 20 is an outlier.
Patterns
Recurring regularities or arrangements within a dataset, which can include clusters, gaps, or cyclical behaviors.
Example:
A scientist might look for patterns in weather data, such as a recurring cold front every winter.
Positive correlation
A relationship between two variables where both tend to increase or decrease together.
Example:
There is often a positive correlation between the amount of time spent exercising and an individual's fitness level.
Range
A measure of spread calculated as the difference between the maximum and minimum values in a dataset.
Example:
For test scores from 60 to 95, the range is 35 (95 - 60).
Scales (graph component)
The numerical ranges and intervals marked along the axes of a graph, indicating how the data values are measured and spaced.
Example:
Paying attention to the scales on a graph is crucial; a compressed scale can make small changes appear significant.
Scatterplots
Graphs that show the relationship between two different numerical variables for a set of data, with each point representing a pair of values.
Example:
A scatterplot could illustrate the relationship between the number of hours a student studies and their corresponding test score.
Standard deviation
A measure of the average amount of variability or dispersion of data points around the mean of a dataset.
Example:
A small standard deviation indicates that data points are clustered closely around the mean, while a large one means they are more spread out.
Tables and graphs
Visual tools used to organize and display data, making complex information easier to understand and interpret.
Example:
A scientist might use a table and graph to present the results of an experiment on plant growth over several weeks.
Title (graph component)
The main heading of a graph that clearly states what the graph represents or the data it displays.
Example:
Always check the title of a graph first to understand its main purpose, like 'Average Daily Temperatures in July'.
Trends
General directions or patterns observed in data over time or across categories, such as increasing, decreasing, or constant movement.
Example:
Analyzing the stock market, you might observe an upward trend in a company's share price over the last quarter.