Data Types & Terminology
This type of data consists of numerical values where taking an average makes statistical sense, such as height or weight.
What is Quantitative Data?
A common visual trick that exaggerates the differences between groups in a bar graph is failing to start the y-axis at this number.
What is Zero?
A distribution that features a single prominent peak.
What is Unimodal?
Because it is resistant to extreme outliers, this measure of center is the most appropriate choice for describing a highly skewed distribution.
What is the Median?
This type of data places individuals into groups or labels, such as zip codes or eye color.
What is Categorical Data?
This graphical display for quantitative data is constructed using the five-number summary.
What is a Boxplot?
A distribution where the left half roughly mirrors the right half.
What is Symmetric?
This standard measure of variability roughly represents the average distance that data points fall from the mean.
What is the Standard Deviation?
The specific term for the individual item or person from which data is collected, representing a single row in a dataset.
What is an Observational Unit?
Unlike a bar graph, this display groups quantitative data into continuous "bins" or intervals where the bars touch.
What is a Histogram?
A distribution with a long tail stretching out toward the higher values on the number line.
What is Skewed Right (or Positively Skewed)?
This is the formula for a standardized value that tells you exactly how many standard deviations a specific data point is above or below the mean.
(x_i- \mu)/(\sigma) or (x_i - \bar{x})/s or (x_i - mean)/(SD)
This measure of spread captures the middle 50% of the data and is found by subtracting Q1 from Q3.
What is the Interquartile Range (IQR)?
In a boxplot, this specific measure is represented by the vertical line drawn inside the main box.
What is the Median?
If the mean of a dataset is significantly lower than the median, the distribution is likely being pulled by low outliers, giving it this shape.
What is Skewed Left?
If a student scores exactly at the 25th percentile, their score corresponds to this specific boundary in the five-number summary.
What is the First Quartile (Q1)?
To mathematically prove a data point is an outlier on both ends, it must fall below and above this specific formula boundary using the IQR. (2 answers)
What is,
Q_1-1.5 \cdot IQR
and
Q_3+1.5 \cdot IQR?
If a dataset is extremely large, this specific type of graph—which uses a single dot for every individual value—can easily become cluttered and unreadable.
What is a Dotplot?
A distribution where all bins or values have roughly the exact same frequency, creating a flat top across the graph.
What is Uniform?
If a data point is located strictly below the mean, its calculated z-score will always have this mathematical characteristic.
What is a negative sign?