Measures Of Central Tendency Flashcards
Mean
Twkes in all data so susceptible to outliers if infkuenced by high or low values
Median mode midrange
Median middle point
Middle point , so not influence d by outliers
And if the mean values are reflective then use otherwise median better
Midrange is halfway through, add them and divide by 2
This can be influence by out,Kerensky, and assumes data is symmetrical
Calculating median from frequency table?
Frewuency x X/ total frewuency
If grouped then your x is the midpoint between two values, this is an average
Median frewuency table
Find half the frewuency and do extra
Olstion
Do how much extra x class width x frewuency adding kn tk lrefuidh vs,he for x
Mode Kost Freundchen
Midrange add highest snd lowest dive by 2
How to find any median if itsgrouped vs non grouped
If grouped then divide by 2
If non grouped add 1
Double check median approach correct sometimes because might be off by a bot
How to find mid interval values?
Bsdicslly if it’s not over,spping then have to do rounded upper bound thing
EXCEPT IF ITD AGES, THEN IT GOES TI THE NEXT BE FAREFUL
Calm again don’t listen k them if median and grouped divide by 2t
If median and ungrounded add one divide by2, and don’t use extra
Oration veusse it’s easy to just look with cumlaitvefrewuencies
Diffeeence between range and midrange
Range is highest - lowest
Midrange is highera + lowest divide by 2
Auartiles
First is minimum
Second is lower
3drd median 4th upper 5th max
And the thing is from Esch line one to other represents 25% of data so Yh
Compare them
- higher median means HIGHER AVERAGE
- IQ RANGE shows kiddle spread of 50%, more spread means mkre variable less means kess
- range too three thingd
How to find qurtilles?
Find median and REMOVE IT if odd or ignore if even then find medians if others like normal
Again compare box plots
Ranges are similar
But lower IA range means data less spread out
Finally median higher thus on average better
Identifying outliers using quartile
If any value of data is 1.5 x IQR above UPPER
Or 1.5 below lower
Then it can be considered outlier!
Cunlitive frewuency graohs
Plot upper bound against cumulative frequency
Then total FREQUENCY ADIVE by 2 and 4 and 3/4 gives auartile
0 is the first value
Can be stretched for like 10 % is just 10 of frewuency so form 10l 20 and find the data
Standard deviation formula
For grouped values midpoint is x
This is f x2
X2 first then multipliedf
Not fx 2
Mean is still fx /f
Standard is f x2
