Measure of central tendency Flashcards
Mean
the average
sensitive to outliers
median
the middle number
a measure of the LOCATION rather than the spread of data
when there is an even number of data points, what is the median
median is the mean of the two middle numbers
T/F the median is not affected by outliers
TRUE
what happens to the median and mean in NEGATIVELY skewed data
median > mean
mode
most common number
- very resistant to outliers
always the PEAK of the graph
mode and distribution of data
single mode = unimodal
two peaks = bimodal
more = multimodal
normal distrubtion
= guassian distribution
symmetrical and bell-shaped
in normal distribution describe mean median and mode
mean = median = mode
types of normal distrubtion
the flatter and wider the curve
the greater the standard deviation
standard normal distribution
speacial case of the normal distribution where the mean is zero and the standard deivation is 1 == Z distrubition
Negative skew
abnormal distrubction where data falls heavily on the LEFT side
mean median and mode in negative skew
mean median mode from left to right
positive skew
fall on the RIGHT
mean median mode right to left
for skewed distribution what is the better representative of central tendencey
median
better than mean
log-normal distribution
skewed data on ARTHIMETIC scale
normal distribution on logarithmic scale
binomial distribution
probability distrubition of possible outcomes from a series of data when they are:
- only TWO mutally exculsive outcomes (e.g. boy girl)
- probability of the event is the same
poisson distribution
probability of occurence of RARE events in a large populationT
T distribution
a symmetrical distribution that becomes more like the normal as the sample size increases
- useful for analyzing numerical data
- used in hypothesis testing
Chi-squared distribution
a RIGHT skewed distribution taking positive values
- useful for categorical data
becomes more symmetrical as it approaches normality
