Module 4

Question 1

What is a research question?

Answer 1

Forms the basis of the objectives and hypotheses. It should address your population of interest, an intervention, a comparison group, and the outcome you are interested in investigating

Question 2

What are objectives?

Answer 2

Define the specific aims of the study. As such, they need to specify the experiments that will be undertaken

Question 3

What is a hypothesis?

Answer 3

It states the predicted research outcome; the null hypothesis (the opposite of what is predicted) is waht can be rejected in hypothesis testing. Should be stated at the beginning of an experiment

Question 4

What is the aim of experimental studies

Answer 4

Establish causation by introducing a factor or change in order to rule out alternative causes for the resulting observation.

Question 5

What is randomization?

Answer 5

Random allocation of participants to intervention and control groups. Aims to ensure groups are as similar as possible at the start of the study - accounts for known and unknown factors that may affect outcome

Question 6

What is local control?

Answer 6

Practice and techniques used to ensure the intervention is applied uniformly and under standard conditions

Question 7

What is replication?

Answer 7

Repetition of the experiment on many experimental units is needed to provide an estimate of experimental error. Number of replications is sample size

Question 8

What are the 3 main purposes of experimental health research?

Answer 8

1- Discovery
2- Demonstrating efficacy and establishing safety
3- Monitoring effectiveness

Question 9

What is meant by discovery in experimental health research?

Answer 9

Aims to advance fundamental knowledge about human biology

Results from such research may not be immediately used to improve human health

Question 10

Describe basic research

Answer 10

• Discovery-based
• Focused on developing theories
• Aims at furthering knowledge
• Real world applications are not involved at this stage

Question 11

Describe preclinical studies

Answer 11

• Uses cell cultures of animals to monitor the effects of an intervention or treatment before it is tested in humans.
• Focus on evaluating the efficacy and safety of a potential treatment for humans.

Question 12

Describe clinical trials

Answer 12

• Trials in humans
• Designed to evaluate effectiveness of an intervention
• Often split into 2 functions: prevention of illness or disease (prevention trial) and treating a disease or illness (therapeutic trial)
• May either treat the individuals or groups as the experimental units

Question 13

What are 4 important concepts of experimental research?

Answer 13

• Independent and dependent variables
• Causation
• Experimental and control groups
• randomization

Question 14

What is the independent variable?

Answer 14

It is the controlled or manipulated variable by researches in order to observe the effect on the dependent variable
- Also called exposure, treatment, or intervention

Question 15

What is the dependent variable?

Answer 15

What the researcher is most interested in monitoring

- Also called endpoint or outcome

Question 16

What is the role of experimental evident in assessing causality?

Answer 16

Experimental manipulation of the independent variable leading to changes in the dependent variabl provides the strongest evidence for causality

Question 17

What is causality?

Answer 17

A cause-effect relationship between independent and dependent variables

Question 18

What is a control group?

Answer 18

Subset of participants in an experiment that is not exposed to the independent variable

Question 19

What is an experimental group?

Answer 19

Subset of participants that is subjected to the independent variable
- also called treatment group or intervention group

Question 20

Why do we need a control group?

Answer 20

• Provide a baseline measurement that can be compared to the experimental group
• Help uncover relationship between independent and dependent variables because control group is subjected to all the same conditions except independent variables

Question 21

What is a placebo?

Answer 21

A substance or a product having no therapeutic effect

Question 22

What are lurking variables?

Answer 22

Hidden variables that affect the independent and dependent variables
Also called confounding variables

Question 23

What are the 3 types of randomization

Answer 23

• Completely randomized design
• randomized block design
• matched pairs design

Question 24

Describe completely randomized design

Answer 24

All experimental units are randomly assigned to treatment groups

Question 25

A researcher wants to conduct an experiment to determine which environment is best suited for studying – a library, in one’s own room or outside. A total of 30 university students volunteer to participate in the experiment. Which type of randomization would be used?

Answer 25

Completely randomized design.

There are 3 treatments and 10 students will be assigned randomly to each

Question 26

What is a randomized block design?

Answer 26

Instead of directly assigning individuals to groups. They assign them to “blocks” based on a characteristics they believe has an effect on the study (eg: gender) first. Then the each block will be randomly assigned evenly to the treatments

Question 27

A researcher wants to conduct an experiment to determine which environment is best suited for studying – a library, in one’s own room or outside. A total of 30 university students volunteer to participate in the experiment. The researcher believes that gender has an effect on the results. Which type of randomization would be used?

Answer 27

Randomized block design
The researcher will first put the student into 2 blocks, male and female. Then he will assign 1/3 of the females and 1/3 of the males to each treatment

Question 28

What is a matched pair design?

Answer 28

Only comparing TWO treatments by using the same, or similar, experimental units

Question 29

What type of gasoline is more efficient? Type A gasoline or Type B gasoline? 3 cars will be used in this experiment. Which type of randomization would be used?

Answer 29

Matched-pair design, using the SAME experimental units

Researchers will use each 3 cars to test Type A and Type B gasoline subsequently and compare the results

Question 30

A researcher is trying to determine whether or not sleep deprivation has an effect on test scores. Which type of randomization would be used?

Answer 30

Matched-pair design, using SIMILAR experimental units

Researchers will pair students with similar GPA and then they will be split up into the 2 treatment groups

Question 31

What are the 3 common measures and analyses ?

Answer 31

• Risk measures
• Effect measure for time-to-event (survival) outcome
• Intention-to-treat analysis

Question 32

What is a risk measure?

Answer 32

Probability of the endpoint occurring over a defined period of time. Given by the number of units in which the endpoint is observed divided by the number of units that were observed during the period of time.
Also called: Incidence or incidence proportion

Question 33

What is the risk difference?

Answer 33

Probability of the outcome occurring in the treatment group minus probability of it occurring in the control group
Also called: Absolute effect size or treatment effect

Question 34

What is the relative risk?

Answer 34

Ratio of probability of the outcome occurring in the treatment group and the probability of it occurring in the control group
Also called: relative probability or relative likelihood

Question 35

What is the hazard rate?

Answer 35

Speed at which the outcome is observed. Given by the number of units in which the outcome is observe divided by the sum of time each unit is observed
Also called: Incidence density or incidence rate

Question 36

What is the hazard ratio?

Answer 36

Speed at which unit in the treatment group develop the outcome divided by the speed at which units in the control group develop the outcome
Also called: rate ratio

Question 37

What is the survival proportion?

Answer 37

Proportion of units who survive (do not develop the outcome) over a defined period of time.
Also called: Probability of survival or survival

Question 38

What are effect measures for time-to-event?

Answer 38

For each experimental unit, time-to-event data consists of the following
- Length of time during which the outcome was not observed
- Indicator of whether the end of that period resulted in the outcome being observed or just the end observation
Frequently used in experimental studies as they allow examination of the time elapsing before the outcome occurs

Question 39

What happens if, when measuring time-to-event, the event has not occurred in some experimental units

Answer 39

The observations are referred to as ‘censored’. The relevant time is only known for the units with the outcome, it is not appropriate to analyze time as a continuous variable.
Censored observations would have to be excluded, which introduces bias

Question 40

What is intention-to-treat analysis?

Answer 40

Includes all randomized patient in the groups to which they were randomly assigned, regardless of their adherence with the entry criteria, regardless of the treatment they actually received, and regardless of subsequent withdrawal from treatment or deviation from the protocol
- once randomized, always analyzed-