Random leaf sampling

I need help! I need to find a method in which i can randomly pick leaves off an oak tree minimising bias.
The best way would be label all of the leaves and use a random no generator but thats just silly..........

Reply 1

rock_eleven

*checks calendar*

theres no exams around now, so im guessing its homework? The solution is not to do it

Reply 2

Spurs

ermm u could say you are going to pick a leaf every 5cm or soemthing like that that is fairly random

Reply 3

kiran123

produce co-ordinates along the hedge or what ever your sampling
for my coursework i split the hedge into three parts bottom middle and top
then picked a leaf roughly from each areaafter generating random numbered co-ordinates, in reality i just picked leaves from anywhere because it was snowing that day! oh well

Reply 4

Sags_3

It actually coursework which we have to plan in the lesson tomorrow. We do our coursework under exam conditions so no taking it home.
Well if you took a leaf every 5cm down a oak tree branch, what do you do if you get to a junction where it splits into 2 branches? what if you reach a point at which there are 5 leaves? so many places where you can have error and bias.

Reply 5

steve2005

Sags_3

How many leaves do you need. Lets suppose you need 20. Pick 100 off the poor oak tree. Put them in a bag and then shake the bag and then take out the first 20 .( Obviously don't look in the bag when picking a leaf) You could wear gloves - so that ' feel ' was eliminated as a source of bias. If a leaf felt ' funny ' you might be tempted not to pick it.

Reply 6

kiran123

it doesnt matter about the bias its meant to be there so you can make a good evaluation and say that your results are not entirely accurate. just say that you will always follow the main branch, not any smaller extensions of it to minimise error, but remember its a coursework they want you to pick up on the fact that error is inevitable

Reply 7

Sags_3

The syllabus states we must not be destructive to the environment so no picking leaves off trees, and its a minimum of 100 leaves.
Yes we do have to have one bit of bias so we can talk about improvements etc, but you dont want so much bias that you lose marks on your plan.

Reply 8

kiran123

i got an A in my coursework! the thing about the bias is that the factors that you cannot control like the branch structure (environmental factors) is something they want you to pick up on, if you yourself make silly mistakes eg only sampling north/south facing leaves which may recieve more/less light then that would increase error. now that would down mark your plan

Reply 9

Tom

Pick whatever ones you like (i suggest those easiest to reach / that provide most interesting stuff to write about in the CW) and the LIE about picking randomly. That style of solution never failed me in a piece of science CW. They provide stupid hoops to jump through, but no-one's making you actually jump through them for real.

I mean, c'mon, can anyone say with honesty they have ever done a whole SC1 without fabricating at least some of the results to fit the pattern you are supposed to find / provide more stuff to write about / allow you to jump through some hoop?

Reply 10

Sags_3

hmmm dont think you can just pick any leaves that you want the mark scheme states plan a samplimg method which has to be explained in detail in the planning section.
Ive done the planning part this morning so cant really go back. Im investigating the number of galls per leaf in inner and outer canopy of oak tree.