Graphs and Diagrams
Definition: Diagrammatic and graphical presentation displays data visually so comparisons and trends are immediately clear.
Diagrams (for comparison)
Bar diagrams (simple, multiple, sub-divided), pie charts, and pictograms.
Graphs (for frequency distributions)
- Histogram — bars for continuous class intervals.
- Frequency polygon — line joining midpoints of histogram tops.
- Ogive — cumulative frequency curve (less-than / more-than); their intersection gives the median.
Real-world example: An ogive lets you read off the median and quartiles graphically, without direct calculation.
Solved Examples: Graphs
Example 1. The cumulative frequency curve is known as an:
- Ogive.
Example 2. The point where the "less-than" and "more-than" ogives intersect gives the:
- Median.
Example 3. A frequency polygon is formed by joining the ______ of the tops of histogram bars.
- Midpoints.
⚡ Speed Tricks & Shortcuts
- Ogive = cumulative frequency curve; the two ogives intersect at the median.
- Histogram bars touch (continuous); bar-chart bars have gaps.
- Frequency polygon joins the midpoints of the bar tops.
Leaving gaps between histogram bars — continuous data means the bars touch.
Graphical and Diagrammatic Presentation — Revision Notes
Quick-revision notes for Graphical and Diagrammatic Presentation — the must-know points for SSC CGL Tier-I/II.
- Diagrams (bar, pie) and graphs (histogram, frequency polygon, ogive) present data visually.
- Bar diagrams compare categories; pie charts show parts of a whole.
- Histograms represent continuous frequency distributions with adjacent bars.
- A frequency polygon joins midpoints of class tops; an ogive is a cumulative frequency curve.
- Ogives (less-than and more-than) intersect at the median.
- Choose the presentation type based on data nature and the message to convey.
Graphical and Diagrammatic Presentation — Flashcards (SSC CGL)
Cover the answer, recall, then check. 6 cards on the must-know Graphical and Diagrammatic Presentation facts for SSC CGL.
Q1. Which chart shows parts of a whole?
A1. A pie chart.
Q2. What is a histogram used for?
A2. Representing a continuous frequency distribution with adjacent bars.
Q3. What is an ogive?
A3. A cumulative frequency curve.
Q4. At what value do the two ogives intersect?
A4. The median.
Q5. What is a frequency polygon?
A5. A line graph joining the midpoints of the tops of the classes.
Q6. How does a histogram differ from a bar diagram?
A6. Histogram bars touch (continuous data); bar-diagram bars have gaps (discrete).