Experiments: Lecture quiz Flashcards
Mill’s method of difference involves setting up two separate systems S1 and S2. What is true about these systems? Mark all correct options.
A)
Using two systems enables us to exclude alternative causes of the observed results.
B)
Any background factors that are controlled in S1 must also be controlled in S2.
C)
If we do an intervention in S1, then we only need to observe the result in S1, not in S2.
D)
Any intervention done on S1 must also be done on S2A
A)
Using two systems enables us to exclude alternative causes of the observed results.
B)
Any background factors that are controlled in S1 must also be controlled in S2.
Which of the following statements about Mill’s Method of Difference are true? Mark all correct options.
A)
Mill’s Method of Difference exhibits the reasoning behind testing hypotheses with experiments.
B)
The main question that Mill’s Method of difference asks is: what causes event E?
C)
Mill’s Method of Difference elucidates the ways in which an experimental process can go wrong.
D)
Although it is an illustrative thought experiment, Mill’s Method of Difference has little to do with how actual experiments are conducted
A)
Mill’s Method of Difference exhibits the reasoning behind testing hypotheses with experiments.
B)
The main question that Mill’s Method of difference asks is: what causes event E?
C)
Mill’s Method of Difference elucidates the ways in which an experimental process can go wrong.
Which of the following empirical practices constitute experiments? Mark all correct options.
A)
Observing the effects of a natural catastrophe on a local economy.
B)
Testing a medical treatment for potential side-effects by giving it to a number of patients and observing their health.
C)
Measuring the temperature of arctic lakes by taking samples at different depths.
D)
Measuring the boiling point of a liquid in a pressure chamber to observe how this changes when you change the pressure.
E)
Tracking the orbits of two of Saturn’s moons to see if they’re affected by each other’s gravitational pull.
B)
Testing a medical treatment for potential side-effects by giving it to a number of patients and observing their health.
D)
Measuring the boiling point of a liquid in a pressure chamber to observe how this changes when you change the pressure.
A team of researchers want to test if a new nanomaterial for jackets that they are developing is more dirt repellent than an ordinary textile material for jackets. For this they plan to conduct a field experiment. What relevant actions for this experiment could they take? Match each action below to Control, Intervention, Observation of the outcome, or Irrelevant or not directly relevant.
A)
Measuring the amount of dirt on the jackets.
B)
Making sure no participants wear any smartphones or communicate with their families or friends during the trial.
C)
Estimating the average age, weight and food intake of the participants during the trials.
D)
Making sure that the participants in the experiment are exposed to similar environments and amounts of dirt, and that the trials are conducted for an equal duration of time
E)
Letting participants wear jackets made of the nanomateria
A)
Measuring the amount of dirt on the jackets.
- Observation of the outcome
B)
Making sure no participants wear any smartphones or communicate with their families or friends during the trial.
- Irrelevant or not directly relevant
C)
Estimating the average age, weight and food intake of the participants during the trials.
- Irrelevant or not directly relevant
D)
Making sure that the participants in the experiment are exposed to similar environments and amounts of dirt, and that the trials are conducted for an equal duration of time
- Control
E)
Letting participants wear jackets made of the nanomaterial
- Intervention
Match the correct description (A-D) with the correct observational practice (1-4).
A)
An observational study where circumstances are organized as if there had been manipulation for intervention and control, but no manipulation is in fact done.
B)
A model study where the model is created as to mimic an experiment, but where the variable that is intervened on is only represented rather than being actually present.
C)
A study without intervention, where some background variables might be (but need not be) controlled.
D)
An experiment where there is manipulation in terms of an intervention but where several background variables are not controlled, in particular not controlled through manipulation.
1) Natural experiment
2) Field experiment
3) Observational study
4) Simulation experiment
A)
An observational study where circumstances are organized as if there had been manipulation for intervention and control, but no manipulation is in fact done.
- Natural experiment
B)
A model study where the model is created as to mimic an experiment, but where the variable that is intervened on is only represented rather than being actually present.
- Simulation experiment
C)
A study without intervention, where some background variables might be (but need not be) controlled.
- Observational study
D)
An experiment where there is manipulation in terms of an intervention but where several background variables are not controlled, in particular not controlled through manipulation.
- Field experiment
Imagine the following scenario.
You are the head researcher at AI Robotics Inc. In six months’ time you are going to release a new line of humanoid robots. You want to know how well they are going to keep their balance doing regular household tasks such as picking up the newspaper, cleaning up, and similar things. To get some data to answer your question, you build a computer program that constructs a virtual 3D environment in the form of a house, and impose artificial gravity onto the environment. You then import the schematics for the new humanoid robot into this environment and then watch it perform such household tasks in the virtual world.
Did you just perform an experiment? Mark all correct options.
A)
Yes. We controlled the background variables, manipulated our target variable and observed or recorded the outcome.
B)
Yes. Experiments are mostly about predicting what will happen, and this simulation gives us information to base our judgement on.
C)
No. Simulations are not experiments because they do not manipulate the real variables.
D)
No. We constructed an observational study
C)
No. Simulations are not experiments because they do not manipulate the real variables.
Which of the following, broadly construed alternatives describe general types of error in experiments? Mark all correct options.
A)
A failure to intervene on the target variable.
B)
A failure to reconcile the hypothesis with the common sense conception of the investigated phenomenon.
C)
A failure to implement control over background variables.
D)
A failure to correctly observe the outcome of the experiment
A)
A failure to intervene on the target variable.
C)
A failure to implement control over background variables.
D)
A failure to correctly observe the outcome of the experiment
Match each term (1-4) with the correct description (A-D)
A)
An inference about an experimental system is internally valid if there is a relation between intervention and observed effect inferred from the experiments is indeed true and is not confounded by uncontrolled background factors.
B)
A factor influences the selection of the sample or the division into test and control group, creating some effect which one did not aim to create.
C)
The observation is registered incorrectly due to psychological properties of the observer.
D)
The act of observation changes that which is observed.
1) Selection bias
2) Observer effect (influence problem)
3) Confirmation bias (interpretation problem)
4) Internal validity
A)
An inference about an experimental system is internally valid if there is a relation between intervention and observed effect inferred from the experiments is indeed true and is not confounded by uncontrolled background factors.
- Internal validity
B)
A factor influences the selection of the sample or the division into test and control group, creating some effect which one did not aim to create.
- Selection bias
C)
The observation is registered incorrectly due to psychological properties of the observer.
- Confirmation bias (interpretation problem)
D)
The act of observation changes that which is observed.
- Observer effect (influence problem)
Imagine that you are performing an experiment on the heat emission of a certain type of exhaust engine. Your hypothesis is that a new kind of material used in the engine will result in a more even heat emission. You set up a prototype of the engine in a laboratory environment and carefully plan every step of the experimental procedure, including what equipment you will use to control background factors and measure the relevant parameters. You then perform the experiment according to your plan and note the results, which support your hypothesis.
What does it take for your experiment to be repeatable? Mark all correct options.
A)
A separate research team must test the same hypothesis and obtain the same result.
B)
The results as well as the mentioned details about experimental setup, measuring equipment etc. must be published or made available in some way, so that other researchers can take part of the information.
C)
Your own laboratory and equipment must be made available to future researchers.
D)
None of the other alternatives are required. If all steps specified in the question text are taken then, by definition, the experiment is repeatable.
B)
The results as well as the mentioned details about experimental setup, measuring equipment etc. must be published or made available in some way, so that other researchers can take part of the information.
Imagine the following scenario.
You have been tasked to investigate whether Bright Light Therapy affects people’s self-assessments of their level of well-being. You decide to conduct an experiment as a way of providing an answer to this question. A sample is randomly generated from a population of people who’ve agreed to participate in the study. You are now to decide which control measures to implement in your investigation.
Which of the following options are relevant measures for establishing control? Mark all correct options.
A)
You expose only a part of the group to the bright light therapy and only pretend to do so for the remaining people.
B)
You influence the assessments people make of their level of well-being when answering a standardized questionnaire.
C)
You repeat the experiment in different times of the year.
D)
You identify the participants randomly chosen and select only the ones you think will lead to the experimental result you are expecting.
E)
You make sure that the population from which the sample is taken is not skewed in some sense.
A)
You expose only a part of the group to the bright light therapy and only pretend to do so for the remaining people.
C)
You repeat the experiment in different times of the year.
E)
You make sure that the population from which the sample is taken is not skewed in some sense.
Below are examples of different kinds of blinding. Match each example (A-C) with the most relevant type of blinding ( Single, double or experimenter).
A)
The researcher was given two batches of visually identical pills and then administered a randomly chosen pill to each test subject, carefully noting which batch the pill came from.
B)
When designing the survey, we included questions about a wide range of subjects without indicating that the study was only about eating habits.
C)
An external laboratory collected the material samples from both the test and control group and gave each sample a random label before returning them to the researchers.
A)
The researcher was given two batches of visually identical pills and then administered a randomly chosen pill to each test subject, carefully noting which batch the pill came from.
- Double blinding
B)
When designing the survey, we included questions about a wide range of subjects without indicating that the study was only about eating habits.
- Single (subject) blinding
C)
An external laboratory collected the material samples from both the test and control group and gave each sample a random label before returning them to the researchers.
¨
- Experimenter blinding
In some experimental cases, it’s not possible to eliminate all background factors that (might) have a disturbing effect on the outcome. In such a situation, is it necessarily the case that using a model simulation is a preferrable method of investigation? Mark the correct option.
A)
Yes. Disturbing factors always influence tests in ways that must be controlled for through elimination.
B)
Yes. Models can provide us with the data required to answer questions better than an experiment can in almost all instances.
C)
No. It is always possible for us to, in some more or less abstract way, eliminate disturbing background factors. Therefore using a model is not a preferred method of investigation.
D)
No. Disturbing factors cannot always be eliminated. While a preferred control measure in many instances, sometimes it suffices to register different effects separately and take them into account in the analysis of the data.
D)
No. Disturbing factors cannot always be eliminated. While a preferred control measure in many instances, sometimes it suffices to register different effects separately and take them into account in the analysis of the data.
Imagine the following scenario.
You want to test how sensitive a set of plants are to a certain chemical compound. First, you devise a way of safely subjecting such plants to this compound. Second, you prepare yourself to record the levels of certain toxins in the plants throughout a period of two weeks. Before all of this, you wish to separate the plants into a treatment and a control group.
Which methods below can be used for dividing the plants into control and treatment group? Mark all correct options.
A)
Use a lottery wheel to distribute the items based on whether they land on a red or blue area (of which there are equally many) on the wheel, and repeating this process until known disturbing factors only occur in the control group.
B)
Forming a treatment group of the plants that seem healthiest according to some known parameters and putting the rest in the control group.
C)
Use a random number generator and distribute items to the two groups based on whether the number was even or odd, and check that known relevant factors are indeed equally distributed in treatment and control group.
D)
Flipping a fair coin and distributing the groups based on which side it landed, and check that known relevant factors are indeed equally distributed in treatment and control group.
C)
Use a random number generator and distribute items to the two groups based on whether the number was even or odd, and check that known relevant factors are indeed equally distributed in treatment and control group.
D)
Flipping a fair coin and distributing the groups based on which side it landed, and check that known relevant factors are indeed equally distributed in treatment and control group.
What are some purposes for experimenters’ choice of using the method of randomization? Mark all correct options.
A)
Randomization ensures that all background factors are evenly distributed throughout the groups.
B)
Randomization facilitates blinding.
C)
Randomization eliminates the bias of consciously or unconsciously choosing particular items from the sample.
D)
Randomization helps to establish the selection based on one singular factor.
E)
Randomization helps convince others that you have not rigged the treatment/control division in favor of the outcome you want.
B)
Randomization facilitates blinding.
C)
Randomization eliminates the bias of consciously or unconsciously choosing particular items from the sample.
E)
Randomization helps convince others that you have not rigged the treatment/control division in favor of the outcome you want.
What is true about external validity? Mark all correct options.
A)
Randomly choosing a sufficiently large sample from the population is a way to ensure external validity.
B)
The results of an RCT (randomized controlled trial) will by design be externally valid.
C)
Randomly assigning our sample into control and treatment group is a way to ensure external validity.
D)
To ensure external validity we need our sample to be representative of the population.
A)
Randomly choosing a sufficiently large sample from the population is a way to ensure external validity.
D)
To ensure external validity we need our sample to be representative of the population.
