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statistical tools - Coggle Diagram
statistical tools
descriptive statistics
histogram
histogram is one way to organise this information, need statistical measures to help define the center of distribution and the spread around the center
these concepts: central tendency and dispersion
measures of central tendency
often used to describe the typical value in a data set> there are several common types of measures of central tendency
Median
popular summary statistics for demographic data with extreme values or outliers
calculation: group of numbers are ranked from the largest to the smallest
dealing with relatively small number of unusually large or small numbers - many researchers use median
in case of odd numbers, the median is the middle number, eg, 2,3,4,5,7 = ,median is 4
in an even numbers, median is the average of the of the two middle numbers - 2,3,4,5,6,7 = 4+5=9/2=4.5
Mode
value/number that occur most frequently in a data set/observation
mode is primarily used where the distribution has more than one mode
care should be taken to understand what is truly typical of the data values
beware of confounding factors. they may also confuse the results regarding the overall data set. without controlling for these confounding factors, reliance on a single measure of central tendency may produce false/spurious results
Mean
sum of the individual values divided by the total number of cases
using mean in a typical data set can be misleading because it places too much weight on the extreme values.
average
we get huge amount of data everyday. we need a method to organise this information to help us and other people understand better
measures of dispersion : : :
focus on averages may lead us to conclude that one is comfortable in any situation - for instance,standing in cold and hot water
instead of just looking at the central tendency, it is helpful to examine the way the numbers are spread out aorund the center or average. note that the center of the observation is the average/mean value. which is 50% percentile
focusing on the central tendency can obscure other interesting features of the collection of numbers
deviations or differences around the average are summarised by statistical measures termed as variance and the standard deviation (SD)
Variance
: measure of dispersion/spread out of the data around the mean/average value
it is one way of describing how closely individual observations in a data set cluster/group/collected around the mean