Individual Differences, Variability & Interpreting Tests Flashcards
What is the main focus of psychological measurement?
Identifying differences between people in behavior and psychological characteristics.
What are the two types of differences psychologists evaluate?
- Interindividual Differences (between-person differences)
- Intraindividual Differences (within-person differences)
Define interindividual differences.
Differences that exist between different people.
Define intraindividual differences.
Differences within the same people over time or under different circumstances.
What is the importance of identifying individual differences in applied contexts?
Practitioners strive to identify how people vary to tailor interventions and understand psychological phenomena.
What is the role of psychometrics in psychological measurement?
Psychometrics is dependent on accurately identifying individual differences through well-designed measurement processes.
What does reliability in psychological testing refer to?
The consistency of test scores over multiple administrations.
What does validity in psychological testing assess?
Whether differences in test scores reflect true differences in the same attribute.
What statistical concept quantifies variability in a distribution of scores?
Variance.
What is standard deviation?
The square root of the variance, reflecting the size of the raw deviation scores.
What is the central tendency?
- Mean Score (Average)
- Mode (Most Scored)
- Median (Mid-point Score)
How is the mean calculated?
Sum up the total scores and divide by the number of responses.
What is a normal distribution?
A symmetrical distribution of scores around the mean.
What is a positively skewed distribution?
A distribution with fewer scores above the mean, resulting in a skewness score greater than 0.
What is a negatively skewed distribution?
A distribution with fewer scores below the mean, resulting in a skewness score below 0.
What does covariance measure?
The degree to which two distributions of scores vary in a corresponding manner.
What is correlation?
A measure of the strength and direction of the association between two variables.
What does a scatterplot visually represent?
The association between two variables, with each dot representing a person’s score.
What indicates a strong positive association in a scatterplot?
High scores in one variable coincide with high scores in another.
What indicates a strong negative association in a scatterplot?
High scores in one variable coincide with low scores in another.
Fill in the blank: Variance reflects the variability of the _______.
squared deviation scores.
True or False: A high standard deviation indicates less variability in the distribution.
False.
What are some key considerations for interpreting variability?
- Should always be positive (0 or above)
- No criteria to determine what is small or large variability
- Only compare measures scored using the same units
What does a score represented by a dot in a scatterplot indicate?
The location of the dot is based on two different scores.
What can a scatterplot help identify in data?
Extreme scores (outliers) and trends (upward or downward).
What does an upward trend in a scatterplot indicate?
High scores in one variable coincide with high scores in another.
What does a downward trend in a scatterplot indicate?
High scores in one variable coincide with low scores in another.
What does no trend in a scatterplot signify?
No consistency (association) between the two variables.
What is covariance?
Reflects the association between the variability of two distribution scores.
How is covariance calculated?
Identify deviation from the mean in both variables, multiply deviation scores, and calculate mean of cross-products.
What does a variance-covariance matrix display?
Variance of each variable on the diagonal and covariance between variables in the other cells.
What is the simplest form of a variance-covariance matrix?
2 x 2 matrix including two variables.
What does a correlation coefficient indicate?
Both the direction and magnitude of an association.
What range do correlation coefficients typically fall within?
-1 to +1.
What does a correlation value of 0 indicate?
No association between the two variables.
What does a positive correlation value signify?
A positive association between the variables.
What does a negative correlation value signify?
A negative association between the variables.
What is the significance of correlation magnitude?
Indicates the strength of the association (effect size).
What are the classifications of Pearson correlation values?
- .10 to .30 = small (low consistency) * .30 to .50 = medium (some consistency) * .50 to 1.00 = large (strong consistency)
How are correlation coefficients typically represented?
By an r value.
What is the purpose of a correlation matrix?
To present correlations between multiple variables.
What is the raw score in the context of test scores?
The actual number obtained on a test.
What are two facets to consider when interpreting a test score?
- The meaning of the raw score * The psychological implications of this score.
What is a percentile rank?
Indicates the percentage of scores below a specific score.
What are Z-scores used for?
To standardize scores by converting them into standard deviation units from the mean.
What does a positive Z-score indicate?
The score is above the mean.
What does a negative Z-score indicate?
The score is below the mean.
What is the purpose of converting Z-scores into values that are easier to understand?
To help compare scores using a more relatable average.
What is the significance of test norms?
They provide a reference score based on a representative sample.
What is the importance of a reference sample in test development?
It helps provide norms for a test and ensures comparability.
What does a person in the 90th percentile mean?
They scored higher than 90% of the people.
What is a key question to consider regarding how to interpret scores?
Is the raw score above, below, or equal to the mean score?
What can observed (raw) test scores rarely index?
The true amount of a psychological attribute.
What is the purpose of normalised scores?
To help interpret individual scores relative to the average population.
What transformation is conducted for non-normally distributed samples?
Normalised transformations.
What do standard scores help identify?
The degree scores are above or below the mean level.
