Unit 3 - Experimentation

Question 1

Validity

Answer 1

Variables controlled so that any measured effect is likely to be due to the independent variable

Question 2

Reliability

Answer 2

Consistent values in repeats and independent replicates

Question 3

Accuracy

Answer 3

Data, or means of data sets, are close to the true value

Question 4

Precision

Answer 4

Measured values are close to each other

Question 5

What is a pilot study?

Answer 5

Small-scale, preliminary studies which aim to investigate whether crucial components of a main study will be feasible

Question 6

What is a pilot study used for?

Answer 6

To help plan procedures, assess validity, and check techniques.

Question 7

What does a pilot study ensure?

Answer 7

An appropriate range of values for the independent variable.

Question 8

What does a pilot study allow the investigator to do?

Answer 8

Establish the number of repeat measurements required to give representative value for each independent datum point

Question 9

What is an independent variable?

Answer 9

The variable that is changed in a scientific experiment

Question 10

What is the dependent variable?

Answer 10

The variable being measured in a scientific experiment

Question 11

What is the difference between simple and multifactorial experiments?

Answer 11

Simple: One independent variable

Multifactorial: More than one independent variable

Question 12

What is a drawback of simple experiments?

Answer 12

It’s findings may not be applicable to a wider setting

Question 13

What is observational studies?

Answer 13

Where the independent variable is not directly controlled by the investigator, for ethical or logistical reasons

Question 14

What are observational studies good at detecting?

Answer 14

Correlation

Question 15

Why are observational studies less useful for determining causation?

Answer 15

They don’t directly test a hypothesis

Question 16

What is a confounding variable?

Answer 16

Variable, other than independent and dependent, that may affect the results of an investigation

Question 17

Why must confounding variables be held constant if possible?

Answer 17

Their effect on the results can be accounted for in the analysis

Question 18

What can be used if confounding variables cannot be controlled easily?

Answer 18

A randomised block design

Question 19

What is a control?

Answer 19

An experimental group where no treatment is given

Question 20

What are control results used for?

Answer 20

Comparison with results of treatment groups

Question 21

What does a negative control do?

Answer 21

Provides results in the absence of treatments

Question 22

What is a positive control group?

Answer 22

A treatment that is included to check that the system can detect a positive result when it occurs

Question 23

What can placebos be included as?

Answer 23

A treatment without the presence of the independent variable being investigated

Question 24

What is the placebo effect?

Answer 24

A measurable change in the dependent variable as a result of a patient’s expectations, rather than changes in the independent variable

Question 25

What is “In Vitro?”

Answer 25

Refers to the technique of performing a given procedure in a controlled environment outside of a living organism

Question 26

What is “In vivo?”

Answer 26

Refers to experimentation using a whole, living organism

Question 27

Advantage of “In vitro”

Answer 27

Better control of your experiment and any confounding variables

Question 28

Disadvantage of “In vitro”

Answer 28

Not possible for many biological studies

Question 29

Advantage of “In vivo”

Answer 29

Get a better idea of what is going on inside the cell or oganism

Question 30

Disadvantage of “In vivo”

Answer 30

Living organisms show great variability which cant be controlled

Question 31

When is a representative sample of a population selected?

Answer 31

Where it is impractical to measure every individual

Question 32

What should a representative sample share with the whole population?

Answer 32

The same mean and same degree of variation about the mean

Question 33

What is random sampling?

Answer 33

When members of the population have an equal chance of being selected

Question 34

What is systematic sampling?

Answer 34

When members of the population are selected at regular intervals

Question 35

What is stratified sampling?

Answer 35

The population is divided into categories that are then sampled proportionally

Question 36

What is variation in results due to?

Answer 36

The reliability of measurement methods and/or inherent variation in the specimens

Question 37

What is variation influenced by?

Answer 37

Precision and accuracy of repeated measurements

Question 38

How can natural variation in biological material be determined?

Answer 38

Measuring a sample of individuals from the population

Question 39

When can results be considered reliable?

Answer 39

If they can be achieved consistently

Question 40

What is qualitative data?

Answer 40

Subjective and descriptive

Question 41

What is quantitative data?

Answer 41

Can be measured objectively, usually with a numerical value

Question 42

What is ranked data?

Answer 42

The data transformation in which numerical values are replaced by their rank when the data are sorted from lowest to highest

Question 43

What do box plots show?

Answer 43

Variation within and between data sets

Question 44

What are error bars?

Answer 44

Graphical representations of the variability of data and used on graphs to indicate the error or uncertainty in a repeated measurement.

Question 45

What do large error bars indicate?

Answer 45

High variability

Question 46

What is correlation?

Answer 46

An association and does not imply causation

Question 47

When does Causation exist?

Answer 47

If the changes in the values of the independent variable are known to cause change to the value of the dependent variable

Question 48

When does positive correlation exist?

Answer 48

When an increase in one variable is accompanied by an increase in the other variable

Question 49

When does negative correlation exist?

Answer 49

When an increase in one variable is accompanied by a decrease in the other variable