Human Factors Engineering 1

What are the 4 Scale Levels in order of lowest to highest?

nominal, ordinal, interval, ratio

Classify the scale level: "Tax Class" (Steuerklasse)

nominal

Classify the scale level: "School Grades" (Schulnoten)

ordinal

Classify the scale level: "Temperature in °C"

interval

Classify the scale level: "Price in Euro"

ratio

What are the 3 mandatory characteristics of a true Experiment?

1. Systematic variation of an Independent Variable (IV)

2. Measurement of a Dependent Variable (DV)

3. Control of confounding variables

In an experiment testing if short-wave light suppresses melatonin compared to long-wave light, what is the IV?

wave light

What is a Quasi-Experiment?

Independent Variable is manipulated, but random assignment of subjects to groups is not possible

What is the primary purpose of the Solomon Four-Group Design?

evaluate whether a pretest influences the results of an experimental treatment.

Name 3 of the 7 threats to validity in quasi-experiments (Campbell & Ross).

1. History (external events)

2. Maturation (natural aging/trends)

3. Pre-testing effect

4. Unstable measurement

5. Regression to the mean

6. Diffusion of treatment

7. Instability of variables

What is the difference between a Sign System and a Category System in observation?

Sign System: Logging specific, predetermined, concrete behaviors (e.g., tool usage).

Category System: Abstracting behaviors into broader conceptual groups (e.g., "productive" vs "idle").

A database records employees' telephone numbers. What scale level?

Nominal

A researcher records the calendar year in which each machine was installed: 2020, 2021, 2022. What scale level?

Interval

A worker completes a task in 10 s, another in 20 s. What scale level is reaction/task completion time?

Ratio

Researchers change workplace lighting from long-wave to short-wave light and measure workers' attention scores. What is the DV?

attention score

Researchers test whether lighting affects performance but keep room temperature, working time, and task difficulty constant. What variables are being controlled?

confounding variables

A factory introduces a new workstation layout. During the study, a major software failure causes workers' productivity to drop. What validity to the experiment threat is this?

history

Engineers compare aluminum, steel, and titanium components and measure how much each bends under the same load. What are the IV variable?

materials

Engineers compare aluminum, steel, and titanium components and measure how much each bends under the same load. What are the DV variable?

amount of deformation

Researchers investigate whether background noise levels influence workers' ability to detect machine alarms. What are the IV variable?

noise levels

Researchers investigate whether background noise levels influence workers' ability to detect machine alarms. what are the DV variable?

workers ability to detect machine alarms