Lecture 4

Question 1

Controlled Experiments

Answer 1

1. Formulate hypothesis
2. Design Experiment
3. Choose subjects
4. Run experiment
5. Interpret results and accept or reject hypothesis

Question 2

Dependent vs Independent Variables

Answer 2

Independent: What explanation is based on (age, expertise)
Dependent: What is tried to explain (usability, time taken)

Question 3

Hypothesis

Answer 3

Claim that implies changing IV influences dependent variable

Question 4

True experiment

Answer 4

Experimenter controls experiment assignments => allows causal conclusions

Question 5

Quasi experiment

Answer 5

Controlled assignment not possible, use other assignment critereon

Question 6

Non experiment

Answer 6

Observation as is, interviews, surveys etc. (No deductable cause).

Question 7

Between group vs Within Group

Answer 7

Between: The effect of some condition is measured between groups
=> Each group experiences one condition
+ cleaner design, no learning, not as tiring
Make sure to assign groups as similar as possible
Within: The effect of each condition is measured within a group
=> The group is testing all condition
+ cheaper
Make sure to lower effects of learning, tiring by randomising order, allowing training session

Question 8

Split plot

Answer 8

Investigate some variables between group and some within group

Question 9

Systematic Errors/ Bias

Answer 9

Measurement Instrument: slow stop watch, bad sensor
Experiment Procedure: learning, fatigue, pressure
Recruiting bias: eg. only recruiting IT students will bias results
Experimenter Behaviour Bias: spoken language, body language
Environmental Bias: no distractions