Ch.4 Flashcards
Mathematical summaries of performance (e.g., the best score) and performance characteristics (e.g., central tendency, variability)
Descriptive statistics
2 types of scores and their # of values
-Continuous Scores: scores with a potentially infinite number of values.
-Discrete Scores: scores limited to a specific number of values.
4 types of scale measurements
-Nominal
-Ordinal
-Interval
-Ratio scale
Key Difference between Interval and Ratio scale
Interval- Zero is arbitrary/means something
Ratio scale- Zero exists and indicates lack of value (ex: height)
Way to remember the scales of measurement
•Nominal: categories, name, classify
•M/F (code or labels)
•Ordinal: ranked order – no information in spacing
•Placing on podium
•Interval: order + spacing units – zero is arbitrary
•Temperature, knowledge tests
•Ratio scale: order, spacing units, zero exists (absolute)
•Height
The percentage of observations that fall AT a given point and BELOW that point. norm referenced
Percentile
Order of operations
PEMDAS
What is the most frequent value?
Mode
What 3 modals are there in mean? (# of averages)
-Unimodal
-Bimodal
-Multimodal
What CT measure is Independent of distribution shape and very useful with skewed data
Median
What CT measurement calls for attention to values that cluster & good for rough estimates?
Mode
3 types of Central Tendency measures?
Mean, Median, Mode
A graph consisting of columns used to represent the frequencies of observed scores in the data
Histogram
Normality: Measure of the normality of the data
Skewness
Normality: Measure of the “pointness” of the data (Can be “peaky” or flat)
Kurtosis
Acceptable limit for both skewness and kurtosis statistics
± 2.0
What scewness bumps at the left and which one at the right?
-Positively (left)
-Negatively(right)
Order of CT measures from left to right on graph
Mean Median Mode
3 types of kurtosis
-Leptokurtic
-Mesokurtic
-Platykurtic
How spread out the distribution is
Variability
Measures of the center of the distribution
Central Tendency
3 types of Variation measures
-Range
-Variance
-Standard Deviation
What is Variance and what is it known as?
-Spread of scores based on the squared deviation
-How close the scores are in the middle
-ERROR
-Explains how spread out scores/values are in a distribution
-Indicates how much the values deviate from the mean of the distribution
Standard deviation
Express a particular score in terms of how many standard deviations it is away from the mean in a normal curve
Standard score/ Z-score
T/F: z-scores have a mean score of 0 and standard deviation of 1
True
