Central Tendency Flashcards
Mode
Most common score
Must put numbers in order
Central Tendency
A way for us to characterize a group of data into one number that summarizes everyone’s score.
Essential to understand how one individual’s score compares to the rest of the group
The Median (mdn)
The score at the 50th percentile
(n+1)/2 th
The Mean
“The Average”
Most common measure in Central Tendency
Sample Mean: M=X *note-M is underlined and X is underlined above
Population Mean: μ
M=Σχ/Ν
Positive Skew
If the mean and the median are greater than the mode
Negative Skew
If the mean and median are less than the mode
Normal Skew/Curve
Mode, Mean, and Median are the same number
Scales of Measurement
Nominal. Ordinal. Interval. Ratio. Skewed
Mode Yes. Yes Yes. Yes Yes
Mdn. No. Yes. Yes. Yes. Yes
Mean No. No. Yes. Yes. Yes
Deviation
How far is each score from the mean
Σ(χ-Μ)=0
Interval/Ratio
Line graph
Nominal/Ordinal
Bar graph
Variability
Tells us how much our scores differ from one another
Range
How far it the lowest score from the highest
Tells us about spread of data
Range=Χh-Xl
Only Ordinal, Interval, and Ratio
Variance
The squared average distance of the scores frm the mean
Sample: s^2
Population: σ^2
Always 3 decimals
Standard Deviation
A measure of the average distance of each score from the mean
Sample: s
Population: σ
