Comments on: Mr Brewin’s Year 12 Stats

By: Mr Brewin

Mr Brewin — Fri, 10 Jul 2009 14:21:01 +0000

Sorry Rachel – a bit of work going on on the blog – but I’ve uploaded the files!

See most recent post.

Best,

By: Rachel 9W

Rachel 9W — Fri, 10 Jul 2009 14:00:26 +0000

erm…I know I am in COMPLETELY the wrong place but could you tell me where you put the Year 9 Stats slideshows so I can print them off. Thanks
Rachel

By: Mrs Tibble

Mrs Tibble — Sun, 11 Jan 2009 16:13:25 +0000

WILL YOU PLEASE USE BRACKETS! – AND, YES, I KNOW I’M SHOUTING
AAAAAAAAGGGGGGHHHHHHHH!

By: DEXTER

DEXTER — Sun, 11 Jan 2009 16:11:01 +0000

and i meeant 30+1/2

By: DEXTER

DEXTER — Sun, 11 Jan 2009 16:10:36 +0000

ooh i get it fanx

By: Mrs Tibble

Mrs Tibble — Sun, 11 Jan 2009 15:55:20 +0000

Deola, if there are 15 leaves, then the middle one is number 8!
(15 + 1) / 2 is not the same as 15 + 1/2!!!!
If the two middle items are the same, then that is the value of the median; if they are different, take their mean.

By: DEXTER

DEXTER — Sun, 11 Jan 2009 15:50:44 +0000

also…with stem and leaf diagrams, when asked to find the median: if we do 15+1/2=15.5. Does one round up to 16 (like with discrete data)or leave it at 15.5 and then read it off the table?

By: DEXTER

DEXTER — Sun, 11 Jan 2009 14:21:24 +0000

thanx Mrs T,

so basically i always use n+1/2
but if there are 50 pieces of data, isnt it simpler to just divide it by 2 and get 25….ooooooh i understand now why i cant do that
okaii thankyou

By: Mrs Tibble

Mrs Tibble — Sun, 11 Jan 2009 14:06:32 +0000

Hi Deola,

1) (n+1)/2 which locates the middle item for an odd number of items, and halfway between the middle two for an even number of items.
eg if there are 50 pieces of data, there are 2 middle items – nos 25 and 26 – and the median is hafway between them at position 25.5 (which is half of 51 not 50)

2) Yes

Tea Lady

By: DEXTER

DEXTER — Sun, 11 Jan 2009 14:02:45 +0000

Hi,
Umm… i need to check a few things with u quickyly:
1) calculating the median…can u just do n/2 or must i always use n+1/2?
2) class boundaries: if the classes are like, 30-35, 35-40. would the class boundaries just be 30 and 35?