T Score Calculator – Guide & Formulas
Convert raw scores to T-scores or calculate t-statistics for hypothesis testing.
Perform standard T-score conversions (where mean=50, SD=10) or calculate a student's t-statistic for sample comparisons. Ideal for psychometrics, education grading, and quantitative lab research.
Key Takeaway
Use the free T Score Calculator to convert raw scores to t-scores or calculate t-statistics for hypothesis testing. Get instant results with step-by-step explanations.
How to Use the T Score Calculator
- Choose the mode: Standardize Score (Psychometrics) or T-Statistic (Hypothesis Testing).
- For Standardize Score, enter the Raw score, Mean, and Standard Deviation.
- For T-Statistic, enter the sample mean, population mean, standard deviation, and sample size.
- Review the calculated scores and statistical significance outputs.
The Formula
Variable Definitions
- x: The raw input value
- μ: The population or historical mean
- s / σ: Standard deviation
- n: Sample size
Standardizing a Psychology Test Result
A psychologist wants to find the standard T-score of a patient who scores 115 on a clinical anxiety index where the norm average is 100 with an SD of 15.
- Step 1: Input raw score = 115, Mean = 100, SD = 15.
- Step 2: Calculate the Z-score: (115 - 100) / 15 = 1.0.
- Step 3: Convert to T-score: 50 + 10 * (1.0).
- Step 4: The patient's clinical T-score is 60.
Frequently Asked Questions
What is a psychometric standard T-score?
A T-score is a standardized scale with a fixed mean of 50 and a standard deviation of 10. A T-score of 60 is exactly one standard deviation above the mean.
When is a t-statistic used instead of a z-statistic?
Use a t-statistic when the population standard deviation is unknown, or when your sample size is small (typically n < 30).
What do degrees of freedom represent in a t-test?
Degrees of freedom (df) generally equal n - 1. It reflects the number of values in the final calculation of a statistic that are free to vary.