variance let' look at histogrambecause variance and standard deviation are all about the spread of the datathe shape of the distribution of dataset take look at the following histogramlet' say that we have some data on the arrival frequency of airplanes at an airportfor exampleand this histogram indicates that we have around arrivals per minute and that happened on around days that we looked at for this data howeverwe also have these outliers we had one really slow day that only had one arrival per minutewe only had one really fast day where we had almost arrivals per minute sothe way to read histogram is look up the bucket of given valueand that tells you how frequently that value occurred in your dataand the shape of the histogram could tell you lot about the probability distribution of given set of data we know from this data that our airport is very likely to have around arrivals per minutebut it' very unlikely to have or and we can also talk specifically about the probabilities of all the numbers in between so not only is it unlikely to have arrivals per minuteit' also very unlikely to have arrivals per minutebut once we start getting around or sothings start to pick up little bit lot of information can be had from histogram variance measures how spread-out the data is