How do you structure an evaluation question?
1) give for and against arguments (NO conclusion needed) always analyse the language used in the question some is deliberately vague causing the reader to make assumptions and can mentioned in ‘against’ arguments
2) give some only/but statements
What are some examples of only/ but statements?
1) there are no data for an increased frequency or lower dose
2) small sample size
3) people vary in size/ age/ ethnicity/ sex
4) only trialled in [mice], not humans
5) only one drug tested
6) only trialled for a [short] period of time (can use this even if study is 10 years long)
7) unknown side effects of treatment
What must you do when given a describe question?
Quote data from the source you’re given
What should you do in a compare question?
Give both similarities and differences
What should you do in a contrast question?
Give only differences
What can you treat a justify, suggest or show question as?
Answer them like an explain question
Give some examples of common against points for evaluate questions
1) no statistical tests were carried out/ no standard deviation so you can’t tell how significant the difference between data values is
2) for a drug e.g. to reduce stiffness all patients still had some degree of stiffness so not completely effective (results will never show a complete solution/cure) - an example of a ‘for’ argument for this is: compared to no drug given all patients experience reduced stiffness
Give some example points for a compare and contrast question on the structure of starch and cellulose
**1) both contain carbon, hydrogen and oxygen
2) both are polysaccharides
3) both have glycosidic bonds
4) cellulose has microfibrils whereas starch doesn’t ** (had to say these first 4 points to get full marks on the similarities!)
5) starch is helical whereas cellulose is straight
6) cellulose has beta glucose monomers, starch has alpha glucose monomers
7) cellulose has 1-4 glycosidic bonds, starch has 1-4 and 1-6 so is branched unlike cellulose
Top tip for when using mark schemes to see how to structure questions?
Don’t only put the points on the mark scheme, you have to write more than is on there to get full marks
How should you do ratios?
Always do ratios to 1!! E.g. 30:1
How do you structure describe and explain questions?
Describe - start with ‘as IV increases, DV …’ then say at what rate e.g. increases at a decreasing rate (copy the IV and DV headings straight into your sentence to avoid making incorrect statements), then quote data, try to give 2 pieces of data for each answer!
Explain - look at the question for clues as to what knowledge you need to use
What should you do when answering a conclusions question?
1) Quote the IV and DV from the question so you don’t accidentally infer invalid conclusions
2) use all the information you’re given if you need to draw multiple conclusions for one question (e.g. a graph might have differently shaded lines that represent extra information)
What is a key thing to remember when describing graphs?
Correlation doesn’t imply causation! Often graphs will only show the effect of 1 factor on another, we don’t know whether something else actually causes it (/has a higher incidence)
What is a confounding variable?
A factor in a study that influences the independent and dependent variables, distorting their true relationship, potentially leading to incorrect conclusions
What is the difference between reliability, accuracy and validity?
Reliability - consistency (repeatedly achieving the same results)
Accuracy - how close a measurement is to the actual value
Validity - how much a study accurately reflects what it claims to measure
Why are repeat measures taken?
To identify anomalous results and calculate a mean/ average
How is a control experiment set up?
In the same manner as the rest of an experiment (except without the key factor/ active ingredient being tested)
How are the results of a control experiment important in interpreting results of an investigation?
They allow a comparison between the use of e.g. a drug versus not using it to show whether it’s effective or not
What should you never say when giving some examples of control variables for a practical?
NEVER say ‘size’ as it’s too vague! Say length or diameter etc (depending on question)
