Measures of central tendancy Flashcards
the “Mu” symbol =
population mean
The “X-bar” symbol =
Sample mean
Population mean (Mu) equals
The sum of the value of each score “x” (numerator) divided by the number of scores (denominator) aka: sigma X-sub-i DIVIDED by N note capital (N) for population
Sample mean (x-bar) equals
x-bar equals sigma x-sub-i DIVIDED by n note small (n) for sample
median =
Middle 50% is more than and 50% is less than (true middle, order the scores and find the middle)
Measures of Central Tendency are
Median Mode Mean
mode=
most common or frequent value
What shape is create when the median mode and mean are all the same
Bell Curve
Skew is described as
the outliers, what is being pulled away from the majority (smaller longer end of the curve)
a long tail to the left is
negatively skewed
a long tail to the right is
positively skewed
The —— is heavily influenced by skew
mean
The —— is moderately influenced by skew
median
The —– is almost immune to skew
mode
The highest point of a frequency distribution will indicate the
mode
is the mean or the median more influenced by skew
the mean, the median is the middle score so will always be in the middle, but the median is the average and will be heavily influenced by the skew
The —— is especially susceptible to extreme values in a dataset
mean
Mu =
population mean
X bar =
Sample mean
when indicating the number of subjects in a population the symbol used is
N (upper case)
when indicating the number of subjects in a sample the symbol used is
n (lower case)
