Bar graphs and histograms can be used to visualize data distributions. The x-axis of a bar graph or histogram can represent qualitative values, single data points, or intervals defined by cut points or midpoints, while the y-axis represents frequency or relative frequency. When analyzing bar graphs and histograms, one should examine the gaps/clusters in the data, the shape of the distribution, any outliers, the central tendency, and the spread or variability of the values. Common distribution shapes include uniform, normal, skewed right or left, and bimodal.

1. Bar Graphs & Histograms
Picturing Distributions with Graphs

2. The X-axis Can Be
1.Qualatative
2.Single Values
3.Intervals labeled by
a) Cut Points
b) Midpoint
Histogram’s Y Axis Can Be:
1.Frequency
2.Decimal Percents/Rel Freq

3. Analysis Should Always Include:
G – Gaps/Clusters
S - Shape
O - Outliers
C - Center
S - Spread

4. G – Gaps/Clusters O - Outliers

5. S - Shape
UniformSymmetric
Normal or
Bell Shaped
Skewed right Skewed left Bimodal

6. C - Center

7. S - Spread

8. Analysis:
G – Gaps/Clusters
S - Shape
O - Outliers
C - Center
S - Spread