Research Methods :Measures of Central Tendency and Dispersion Flashcards
what are measures of central tendency
avgs give us info about most typical values in a set of data
mean is the most
sensitive of all central tendency emhtods
why is the mean most sensitive and why is this good
includes all values of data
more representative of data as a whole
-ve of mean
easily distorted by extreme values
e.g 17 - 108 mean increases
therefore doesnt rep dsata well
+ves of median
not affected by extreme numbers so if 98 replaces 17 it remains same
easy to calc once arranged the numbers
-ve of media
less sensitive than mean
as actual values of lower/higher numbers are ginored and extreme values may be important
bi modla
when data sets ahve 2 modes
-VE of mode
crude measure
casue can be quite diffrent from mean and median and therefore not representative of whole data set
when is mode only method you can use
data in categoriees
e.g favourite dessert use modal group to find most typical
when is mode not useful
several modes in a data set
how do you calc rnage
highest- lowest
+ 1
why do you add 1 to range
math corection
allows for fact raw scores either rounded up/down when recorded within research
accounts for margin of error
+ve of range
easy to claculat e
-ve of range (accounting)
only takes into account the two extreme values therefore unrepresentative odf the data as a hwole
range doesnt give a
fair rep of the general distribution of scores
range is influenced by
outliers
range also dont indicate
whether most numbers are closely grouped around the mean or spread out
standard deviation
single value tells us how far scores deviate from mean
the larger the standard deviatio
the rgeater the dispersion or spread within data
if talking about particular cindtionn in particular experiment what does big standard deviation suggests and hwy
not all pt affected by IV in same way
as data widely sopreaf
may be there’s anamolous results
what does low standard deviation show
data tighly clustered around mean
sshowing pt repsonded in fairly similar way
+ve of standard deviation (precise)
more precise measure of dispersion than range
casue includes all vlaues within the final calc
-ve of standard deviation (Extreme )
distorrted by extreme single vlaue
as includes all vlaues in financial calculation
aslo in standard deviation what might not be revealed
extrme vlaues unlike rnage
