Module 6: Research Methods and Statistics Flashcards
Measures of Central Tendency
+ statistics that indicates the average or midmost score between the extreme scores in a distribution
+ also known as Measures of Central Location
What are the different Measures of Central Tendency?
- Mean
- Median
- Mode
Goal of Measures of Central Tendency
Identify the most typical or representative of entire group
Mean
+ the average of all the raw scores
+ equal to the sum of the observations divided by the number of observations
+ interval and ratio data (when normal distribution)
+ point of least squares\
+ balance point for the distribution
+ susceptible to outliers
Median
+ the middle score of the distribution
+ Ordinal, Interval, Ratio
+ for extreme scores, use median
+ identical for sample and population
+ also used when there has an unknown or undetermined score
+ used in “open-ended” categories (e.g., 5 or more, more than 8, at least 10)
+ for ordinal data
+ if the distribution is skewed for ratio/interval data, use median
Mode
+ most frequently occurring score in the distribution
+ Bimodal Distribution: if there are two scores that occur with highest frequency
+ Not commonly used
+ Useful in analyses of qualitative or verbal nature
+ For nominal scales, discrete variables
+ Value of the mode gives an indication of the shape of the distribution as well as a measure of central tendency
Measures of Spread or Variability
+ statistics that describe the amount of variation in a distribution
+ gives idea of how well the measure of central tendency represent the data
+ large spread of values means large differences between individual scores
What are the different Measures of Spread or Variability?
- Range
- Interquartile Range
- Semi-Quartile Range
- Standard Deviation
- Variance
What are the different Measures of Location?
- Percentile or Percentile Rank
- Quartile
- Decile/STEN
Percentile or Percentile Rank
+ not linearly transformable, converged at the middle and the outer ends show large interval
+ expressed in terms of the percentage of persons in the standardization sample who fall below a given score
+ indicates the individual’s relative position in the standardization sample
+ essential in creating normalized standardized scores
Quartile
+ dividing points between the four quarters in the distribution
+ Specific point
+ Quarter: refers to an interval
Decile/STEN
+ divide into 10 equal parts
+ a measure of the asymmetry of the probability distribution of a real-valued random about its mean
Tools for Correlation
- Pearson R
- Spearman Rho
- Biserial
- Point Biserial
- Phi Coefficient
- Tetrachoric
- Kendall’s
- Rank Biserial
Pearson R
interval/ratio + interval/ratio
Spearman Rho
ordinal + ordinal
