Standardized Scores and Normal Distribution
Probability and Normal Distribution Concepts
Coin Flipping Example:
- Consider an experiment where a coin is flipped 3 times.
- One specific outcome in the sample space is getting zero heads, which represents the explicit outcome sequence of tail, tail, tail.
Normal Distribution Parameters:
- Data values and outcomes can be distributed normally following a standard bell curve.
- The curve is mathematically defined by two primary population parameters:
- Population Mean (): Represents the population average or the central value of the distribution.
- Standard Deviation (): Represents the standard deviation, measuring the variability or spread of the data around the mean.
- Given both and , the exact normal curve can be drawn, enabling the calculation of relative areas under the curve corresponding to probabilities or proportions.
Standardized Scores and Raw Score Conversion
Need for Standardization:
- When working with old-school statistical charts and tables, raw measurements or scores cannot be directly evaluated for standard probabilities.
- The raw score must be converted into a standardized score.
Function of Standardized Scores:
- Conversion to a standardized score rescales raw data relative to the population mean () in units of standard deviation ().
- Standardizing allows the use of standard normal reference tables to determine precise areas under the normal curve regardless of the original raw score scale.