Studies / data

Question 1

What is the aim of studies?

Answer 1

Studies aim to look at how one variable or factor that
changes (the independent variable) affects something else
(the dependant variable), while keeping all other variables
the same (controlled).

Question 2

What are the 5 features of a good study?

Answer 2

1. Clear aim
2. Representative sample
3. Valid and reliable results
4. Sample size
5. Controlling variables

Question 3

What are the 5 Characteristics a good study should have?

Answer 3

 Valid– an investigation that is properly designed to
answer the questions being asked

 Precise– measured in a way that can be
reproduced

 Reliable– can be replicated by different people on
different occasions

 Non biased – not influenced in a particular
direction

 Accurate– an investigation that reaches the proper
conclusions or gets close to the true values

Question 4

What are the three types of studies?

Answer 4

 Longitudinal study – a study carried out over a long period of time.

 Case-control study – an observational study where the subjects are
not randomized to the exposed or unexposed groups. In a case-control
study the outcome is usually known and the investigator is trying to
figure out what caused it. In case control studies, a group of people
that have the disease (cases) are compared with a control group
who do not have the disease. This is a retrospective study.

 Cohort study – is an observational, longitudinal study that uses a
cohort, meaning a group of people with common characteristics. The
outcome is unknown until after the study. Cohort studies follow a
group of people over time to see who develops the disease and who
does not. It is prospective, meaning you want to see who develops
the disease.

Question 5

When scientists design a major study, what can they
do to try and ensure their results will be both valid
and reliable?

Answer 5

 Large sample sizes
 Carry out the study over a long time
 Isolate the factor being studied while keeping all
other factors constant

Question 6

What is a random error?

Answer 6

Random error = a component of ‘measurement error’ that is due
to unpredictable factors that cannot be determined or controlled.
This effect can be minimised by taking many measurements.
Values lying randomly above or below a true value

Question 7

What are the two types of errors?

Answer 7

 Random error
 Systematic error

Question 8

What is a systematic error?

Answer 8

 Systematic error = the extend to which data or conclusions have
been obtained from an investigation that has been suitably
designed to test the hypothesis.
These are values differing from the true value by the same
amount

Question 9

What is validity?

Answer 9

the extend to which data or conclusions have been
obtained from an investigation that has been suitably designed to
test the hypothesis

Question 10

What is a Experimental Group?

Answer 10

– the group that is given a medicine or has a
particular characteristic eg. High fat diet

Question 11

What is a Control Group?

Answer 11

– the group that is given a medicine or has a
particular characteristic eg. High fat diet

Question 12

What is a Null Hypothesis?

Answer 12

in statistics the starting hypothesis states that
there is no difference between the two groups being tested.

Question 13

What is a Alternative hypothesis?

Answer 13

an alternative
hypothesis that states that there is a difference between two
groups. This needs to be proven using statistical tests.

Question 14

What is Statistical testing?

Answer 14

statistical tests used to analyse the data and
determine if the null or experimental hypothesis are correct