Statistics- stem leaf q Watch

Presto
Badges: 17
#1
Report Thread starter 1 week ago
#1
Can someone please clear my doubts?

At first I thought interpolation should be used. Is that possible over here? Can interpolation ever be used in stem leaf diagrams to find quartiles?

If I use 31 (i.e n+1) instead of 30 (n) is that fine or would it lead to the wrong value in other qs like this one?


reply
lionpunkgirl
Badges: 6
Rep:
?
#2
Report 1 week ago
#2
No, you don't need to use interpolation in stem and leaf diagrams.

If you use 31 instead of 30,
Q2(median)=31/2=15.5th term so this works for finding out the median.
BUT
Q1(lower quartile)=31/4=7.75th term and Q3(upper quartile)=(3x31)/4=23.25th term and so it doesn't work for finding out upper and lower quartiles.

However, you can use 31 as detailed in this video but the method is a little different. https://www.youtube.com/watch?v=JK0zHW_ThjY

Hope this helps!
Last edited by lionpunkgirl; 1 week ago
1
reply
Presto
Badges: 17
#3
Report Thread starter 1 week ago
#3
Thank you soo much!
(Original post by lionpunkgirl)
If you use 31 instead of 30,
Q2(median)=31/2=15.5th term so this works for finding out the median.
BUT
Q1(lower quartile)=31/4=7.75th term and Q3(upper quartile)=(3x31)/4=23.25th term and so it doesn't work for finding out upper and lower quartiles.
But in the example they just rounded 7.5 and 22.5 to get 8 and 23 so why can't we just use this and round off the values to 8 and 23 with this too? Would it make a difference in other qs like this? It also worked with example in the video
reply
lionpunkgirl
Badges: 6
Rep:
?
#4
Report 1 week ago
#4
Honestly you probs could but I would just be careful and do the counting method at least to check if you're right for accuracy's sake in exams when trying to find quartiles. It doesn't make too much difference in time so do what you're comfortable with.
0
reply
Presto
Badges: 17
#5
Report Thread starter 1 week ago
#5
(Original post by lionpunkgirl)
Honestly you probs could but I would just be careful and do the counting method at least to check if you're right for accuracy's sake in exams when trying to find quartiles. It doesn't make too much difference in time so do what you're comfortable with.
You're right, thanks!
reply
lionpunkgirl
Badges: 6
Rep:
?
#6
Report 1 week ago
#6
No probs
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • Solent University
    Postgraduate and Professional Open Evenings Postgraduate
    Mon, 25 Mar '19
  • Cardiff University
    Undergraduate Open Day Undergraduate
    Wed, 27 Mar '19
  • University of Portsmouth
    Postgraduate and Part-Time Open Evenings Postgraduate
    Wed, 27 Mar '19

Where do you need more help?

Which Uni should I go to? (149)
18.53%
How successful will I become if I take my planned subjects? (79)
9.83%
How happy will I be if I take this career? (136)
16.92%
How do I achieve my dream Uni placement? (114)
14.18%
What should I study to achieve my dream career? (79)
9.83%
How can I be the best version of myself? (247)
30.72%

Watched Threads

View All