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Reliability, Validity, and Graphs
Reliable means repeats sit close (precision). Valid means you measured what you claimed (the right variable, fair test). A graph is part of the argument: labelled axes with units, a sensible scale, and a line only if the in-between values make sense.
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Reliability, Validity, and Graphs
What is it?
Reliable means repeats sit close (precision). Valid means you measured what you claimed (the right variable, fair test). A graph is part of the argument: labelled axes with units, a sensible scale, and a line only if the in-between values make sense.
In simple words
Reliability, Validity, and Graphs is a core idea in this chapter. Learn the meaning first, then the main parts, then one clear example.
Examples
- Concordant titres named
- Wrong end-point colour
- Zero error on a balance
RELIABLE AND VALID
Three titres within 0.1 cm^3 are precise. If you used the wrong indicator, they can still be invalid. An outlier: check the burette, do not hide it. Accuracy is closeness to the true value (a standard).
TABLES AND GRAPHS
Tables need quantity and unit in the heading, not on every cell. Plot the independent variable on x. A bar chart is for categories; a line is for continuous x (time, temperature). Circle the anomaly.
Recommended for Class 9
Full school-level explanation
Reliable means repeats sit close (precision). Valid means you measured what you claimed (the right variable, fair test). A graph is part of the argument: labelled axes with units, a sensible scale, and a line only if the in-between values make sense.
Numbers, then the picture:
RELIABLE AND VALID
Three titres within 0.1 cm^3 are precise. If you used the wrong indicator, they can still be invalid. An outlier: check the burette, do not hide it. Accuracy is closeness to the true value (a standard).
Remember
- repeats
- right method
Examples
- Concordant titres named
- Wrong end-point colour
- Zero error on a balance
TABLES AND GRAPHS
Tables need quantity and unit in the heading, not on every cell. Plot the independent variable on x. A bar chart is for categories; a line is for continuous x (time, temperature). Circle the anomaly.
Remember
- unit in the heading
- x = independent
Examples
- Time vs temperature cooling
- Do not join bar tops as a 'line' without thought
- Best-fit is not join-the-dots through a wild point
Remember
- reliable = close repeats
- valid = right measurement
- sig figs still apply
- the method still matters
- repeats
- right method
- unit in the heading
- x = independent
How the ideas connect
Scientific notation and prefixes were earlier pages. A result 1.20 x 10^-3 mol is three significant figures if those digits were measured.
Deeper understanding
Go beyond memorising Reliability, Validity, and Graphs. Connect the definition to reasons, relationships, exceptions, and exam wording.
How the ideas connect
Scientific notation and prefixes were earlier pages. A result 1.20 x 10^-3 mol is three significant figures if those digits were measured.
Exam focus
Quick revision
- reliable = close repeats
- valid = right measurement
- sig figs still apply
- the method still matters
- RELIABLE AND VALID: Three titres within 0.1 cm^3 are precise. If you used the wrong indicator, they can still be invalid
- TABLES AND GRAPHS: Tables need quantity and unit in the heading, not on every cell. Plot the independent variable on x.
A computer graph is not automatically valid. Garbage in, a pretty scatter out.
For long answers on Reliability, Validity, and Graphs: define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- reliable = close repeats
- valid = right measurement
- sig figs still apply
- the method still matters
Important formulas
- reliable = close repeats
- valid = right measurement
- sig figs still apply
Common exam traps
- A computer graph is not automatically valid. Garbage in, a pretty scatter out.
- A computer graph is not automatically valid. Garbage in, a pretty scatter out.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
A computer graph is not automatically valid. Garbage in, a pretty scatter out.
- Mistake
A computer graph is not automatically valid. Garbage in, a pretty scatter out.
- Mistake
A computer graph is not automatically valid. Garbage in, a pretty scatter out.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
reliable = close repeats
valid = right measurement
sig figs still apply
the method still matters
Reliable means repeats sit close (precision). Valid means you measured what you claimed (the right variable, fair test). A graph is part of the argument: labell
reliable = close repeats
- Definition
- Reliable means repeats sit close (precision). Valid means you measured what you claimed (the right variable, fair test). A graph is part of the argument: labell
- Formula
- reliable = close repeats
- Example
- Concordant titres named
- Critical warning
- A computer graph is not automatically valid. Garbage in, a pretty scatter out.
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Exam Practice
Define
Q1. Define Reliability, Validity, and Graphs.
Explain
Q2. Explain: RELIABLE AND VALID.
Example
Q3. Give one clear example of Reliability, Validity, and Graphs and say why it fits.
Mistake
Q4. State one common mistake students make about Reliability, Validity, and Graphs.
Exam note
Q5. Write a short exam note on Reliability, Validity, and Graphs: definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.