Experimental design

Question 1

What is the definition of variable

Answer 1

Any factor that can be controlled, changed or measured in an experiment

Question 2

What’s a discrete variable

Answer 2

Can have a finite range of values (bar graph)

Question 3

What’s a continuous variable

Answer 3

Can take on infinitely many uncountable values (line graphs)

Question 4

What do experiments involve

Answer 4

The manipulation of the independent variable by the investigator

Question 5

What’s an independent variable

Answer 5

The variable that is changed in a scientific experiment

Question 6

What’s the dependent variable

Answer 6

The variable that is measured in a scientific experiment

Question 7

What is a control group compared to

Answer 7

Experimental treatment

Question 8

What are the two ways experiments are designed

Answer 8

Simple-one independent variable
Multi factorial- more than one independent variable

Question 9

What is an advantage and disadvantage of simple experiments

Answer 9

Advantage-conducted more easily than in field
Disadvantage- may not be applicable to a wider setting

Question 10

What’s a multi factorial experiment definition

Answer 10

Experiment involves a combination of more than one independent variable or combination of treatments

Question 11

Why do investigators use groups that already exist

Answer 11

So there is no truly independent variable

Question 12

Why is the independent variable not directly controlled in observational studies+ e.g

Answer 12

For ethical or logistical reasons e.g investigating effects of medical conditions

Question 13

What’s a pro and con of observational studies

Answer 13

Pro- good at detecting correlation
Con- do not a hypothesis so less useful for determining causation

Question 14

What’s a confounding variable definition

Answer 14

Variables, other than the independent and dependent variables that may affect the results of an investigation and therefore need to be considered during the investigation

Question 15

When must a confounding variable be held constant or at least monitored

Answer 15

When other variables(confounding)besides the independent variable may effect the dependent variable

Question 16

What is used when confounding variable cannot easily be controlled

Answer 16

A randomised block design can be used

Question 17

How are randomised blocks used to influence confounding variables

Answer 17

Influence so the confounding variable is likely to be the same across treatment and control groups

Question 18

What’s a control definition

Answer 18

An experiment group where no treatment is givin

Question 19

What are control results used for

Answer 19

Used for comparison with the results of treatment groups

Question 20

What’s negative control definition

Answer 20

Provides the results in the ABSENCE of treatments e.g iodine stays brown with water

Question 21

What’s a positive control definition

Answer 21

A treatment that is included to check that the system can detect a positive result when it occurs e.g iodine turns dark blue with startch

Question 22

What are placebos used for

Answer 22

Can be Included as a treatment without the presence of the independent variable being investigated

Question 23

What’s the placebo effect

Answer 23

Is a measurable change in the dependent variable as a result of a patient’s expectations rather than changes in the indépendant variable

Question 24

What is in Vivo definition

Answer 24

Expérimentation using a whole living organism

Question 25

What is in vitro definition

Answer 25

Performing a given procedure in a controlled environment outside of a living organism

Question 26

What’s an advantage and disadvantage of in vitro

Answer 26

A-better control of your experiment and any confounding variables
N-not possible for many biological studies. Not representative of whole organism response

Question 27

What’s an advantage and disadvantage of in vivo

Answer 27

A-better idea of what is going on inside the cell or organism
N-living organisms show great variability which can’t really be controlled