I have a question on block 4, question 6.
It is a graph showing number of children who contracted UTI. Which of the following is the median number of episodes of urinary tract infections for children(n-100) in the sample shown in the graph
a. 0
b. 1
c. 2
d. 3
e. cannot be determined by this graph

Hi.its very easy......

I know that question

it has 4 columns...
first=== 0x 25

2nd column.. 1x 30

3rd column= 2x 10

4th column= 3 x35


add them all and divide with 100 ur ans will be 1.8

so your ans is 1 in options ..i took that 6 form and got it rt

Your calculation is correct but the answer should be 1.55 and rounded to 2.
edited by aquresh1 on 3/9/2011
edited by aquresh1 on 3/9/2011

That seems more like you are finding the mean rather than the median. The median is the middle number so can you explain how that calculation finds the middle number? And why would the answer be 1 anyways if 1.55 is closer to 2?
edited by FeSa21596747 on 3/9/2011
edited by FeSa21596747 on 3/9/2011

I have not seen the actual question but a similar one appears in UWorld. In this case, the mean and median should be close because there are no outliers. The calculation is done this way:

no. of children multiplied with no. of infections [for each value] divided by total number of children which is n [100]

25 children had no infection.
30 children had 1 episode
10 had 2 episodes
35 had 3 episodes

[25x0] + [30x1] + [10x2] + [35x3] / 100
0+30+20+105= 155 / 100 = 1.55

That seems more like you are finding the mean rather than the median. The median is the middle number so can you explain how that calculation finds the middle number? And why would the answer be 1 anyways if 1.55 is closer to 2?
edited by FeSa21596747 on 3/9/2011


HI....well it may be mean and median.....

S0, 1.5 is mean and 1 is median ,which is below the 50th percentile.....

read it in behavioral sciences in STATISTICS...DISTRIBUTION,,,MODE,MEDIAN AND MEAN AND LET ME KNOW

you just calculated the mean.the median is the middle number.the mode is the most occuring number and the range is the difference btw highest number minus lowest number.
Well I just looked at the question and what it asked to calculate is the median so let me help out.
they gave u a chat of 100 children stating that 25 children 0 had uti
30 children 1 had uti,10 children 2 had uti, 35 children 3 had uti
based on normal presentation for you to get the median,u need to express it this way but it will take up ur hours on exam but i will tell u the easy way to calculate it.the difficult long consuming part is since 25 children 0 had uti,u will write 0 in 25 places like 0000000000 in 25 places 30 children,u will express 1111111111111 in 30 places and 10 children only 2 had uti so u express 2222 in 10 places ,and 33333333333 in 35 places then u look for the middle number. but this will take ur time so what u simply do is since 25 children is is 0 uti and 30 children is 1 and 10 is 2,35 is 3
then add 25+30= 55 and 35+10= 45. remember that 25 and 30 are within 0 and 1 uti and 35 and 10 are within 2 and 3 uti so ur median will fall within the 25 and 30 since 30 and 10 are only 45 and 25 and 30 are 50 so the median will be within the 30 children which is now 11111 (5) so the median fall with 1 ao 1 is the median.
for mean it will be add 0+1+2+3 divide by 4
there 6/4= 1.5. ur mean is 1.5
ur mode is 3 cus it is the highest occuring number
ur range is highest minus lowest number so ur range is 3-0 = 3
I hope this helps.
its kinda hard but try read it u will understand cus i am not that good with explanation.my exam is in 2wks and if u wanna discuss biostat or any topic with me,feel free to skype me....GOODLUCK MY FELLOW DOCTORS...

This is it. Thanks for the answer because I got this question wrong too.

There's actually a much easier way to figure this out and better understand it. Like mentioned before, median is the middle value or the 50% value of an organized data (low to high). If n=100, then the value of the 50th sample will be the median. The 50th value is 1 because:
values 1-25= 0(25 kids), values 26-55= 1(30kids), values 56-65= 2(10 kids), and values 66-100= 3(35 kids)

A rule(assuming sequential data 1,2,3,4,5..etc): If sample size is even, your median will always be a full number. If sample size is odd, your median will always be a fraction.
Hope that helps.
edited by on 4/26/2014