Final Exam Flashcards
What are the essential aspects of an experiment?
- IV
-DV - Control (keeps extraneous variables consistent)
- Random Assignment
- Control Group
- Experimental group
What is achieved when your experiment has good control?
what is control?
control = when all other variables other than the IV and DV are held consistent between the two groups
achieve = you can say that the IV caused the DV, and not extraneous variables
what is it called when every participant has an equal likelihood of being assigned to either the experimental or control group?
random assignment
what is the goal of random assignment?
to neutralize individual differences, making the two groups essentially the same
What is a variable that varies along with the IV (due to a lack of control) called?
This variable can serve as an alternative explanation to changes in the DV
confound variable
do confound variables discredit the experiment?
why?
YES
because they serve as an alternative explanation as to why there is a change in the DV that may not be the IV
What is internal validity?
the extent to which the experimenter controls for confound variables.
means that your experiment measured and tested what it was supposed to. (can say that IV caused DV)
ability to say that you tested your hypothesis
are confounds a threat to internal validity?
duh
what are the 4 threats to internal validity?
1) Selection
2) Instrumentation
3) Experimental mortality
4) Experimental Bias
Threats to internal validity:
what is selection?
if the two groups are different somehow before the experiment begins.
Threats to internal validity:
what is instrumentation
changes in criteria used by observers / changes in mechanical measuring device
Threats to internal validity:
what is experimental morality?
loss of subjects in an experiment.
if loss is different ACROSS GROUPS then the study will lack internal validity.
Threats to internal validity:
what is experimental bias?
expectations of an outcome by persons running an experiment may significantly influence the outcome
what is generalizability?
ones ability to say something about a population based on an observed sample…
kinda same thing as external validity
what is external validity?
the extent to which the results of an observation generalize to other situations or are representative of real life.
the degree to which the results of study can be extended beyond the research setting is called what?
external validity
what are 4 threats to external validity?
1) lack of random sampling
2) mortality
3) artificial lab settings
4) reactivity on part of the subjects
threats to external validity:
define: mortality
why is it a threat
loss of participants from a study
if the subjects who drop off are significantly different than thoe who remain the sample may not be representative of the population
(this is called SELECTIVE ATTRITION)
threats to external validity:
why is an artificial lab setting bad?
data obtained in tightly controlled lab settings may not generalize to natural settings
what is the tradeoff between internal and external validity?
high internal validity from tight control lowers external validity…
external validity means it applies the findings in the experiment extend to the real world..
but if the experiment is tightly controlled (has high internal validity) then its not really representative of real life.
Word of the day: Confound
varies with the IV and can serve as an alternative explanation for the change in the DV
if she asks “is this a true experiment” what is the one thing that you look for?
random assignment
define: power
the ability to detect the effects of the Iv if they are actually there
when do we use a Chi Square test?
when we want to test the independence of two variables
is x independent of y?
Chi Square:
what is the null hypothesis?
Variables x and y are independent.
Chi square:
what is the alternative hypothesis?
Variables X and Y are NOT independent
is Chi square a kind of statistical test?
yes!
its an inferential stats test
what is error variance?
- the variability in scores caused by variables other than your IV
(e.g. some subjects might be tired) - can be extraneous or subject related variables
How do you handle error variance?
3 ways + what each thing means
1) reduce error variance
–> hold extraneous variables consistent
–> match subjects on characteristics
–> use within- subject design
2) Increase the effectiveness of your IV
–> use a strong manipulation
–> use sensitive DV
3) Randomize Error Variance
–> use random assignment
what is between-subject designs?
- participants are randomly assigned to the groups
- groups are independent
- different participants in both groups
- its also called independent group design
- its the type of design we do.
what is a within-subject design?
- one participant goes through all levels of the IV
- also called repeated measures design
what are the advantages of within subject designs?
- subject-related factors are literally identical across conditions, so there are not large differences to obscure the effects of the IV
- reduced error variance leads to a more powerful design
- serving as a control for yourself, more likely to find the effect of an IV because there is not as much error variance across groups
what are the disadvantages of a within subject design?
- more demanding on subjects
- there is a risk of carryover effects (order effects) where the previous treatment alters the behaviour in a subsequent treatment
What is the advantages and disadvantages of a between-group design?
– requires more participants to have high statistical significance?
What are the two types of Between-subject designs?
each type has groups within it…
break em down.
1) single-factor randomized group designs
a) randomized two group design
b) randomized multi group design
2) matched group design
a) matched pair design
b) matched multi group design.
ok ok..
what is a randomized two-group design?
what are the advantages and disadvantages?
- randomly assign participants to 2 groups.
advantage: easy to conduct, don’t need a lot of subjects
disadvantage: provides limited information
what is randomized multi group design?
three or more levels of the IV
subjects are randomly assigned
what are the advantages / disadvantages to randomized multi group design?
disadvantage: greater number of subjects needed
advantage: obtain more information
word of the day: Factor
means the same thing as the IV - they are interchangeable
what is a matched pair design?
only two groups are tested
- matched on a certain variable that is important to the experiment
e.g. equalize participants based on math ability if you are doing a algebra experiment
what is matched multi group design?
multiple groups are tested
what are the advantages / disadvantages for matched designs?
advantage: can control subject variables that may obscure the effect of the IV
disadvantage: more demanding and time consuming
carry over effects can happen in ‘Within subject designs’
what are carryover effects (order effects)?
where a previous treatment alters the behaviour in a subsequent treatment
(how you behave in the first condition could effect how you behave in the next)
what are the sources of carry over effects?
x6
Leonard farted happily sensing completion arrival
1) Learning
2) Fatigue
3) Habituation
4) Sensitization
5) Contrast
6) Adaptation
carry over effect:
What is learning?
learning to perform a task in the first treatment may affect later treatments
carry over effect:
What is fatigue?
may cause performance in later treatments to deteriorate
carry over effect:
What is habituation?
repeated exposure to a stimulus can lead to reduced responsiveness
carry over effect:
What is sensitization?
repeated exposure to a stimulus can lead to increased responsiveness
carry over effect:
What is contrast
exposure to one condition may alter responses in later conditions
carry over effect:
What is adaptation
subjects may adapt to certain manipulations (e.g. drug trials)
how do we fix the issue of carry over effects?
counterbalancing
what is counterbalancing?
assign treatments in a different order for different subjects
what are the two different kinds of counter balancing?
complete counterbalancing and partial counterbalancing
what is complete counterbalancing?
provides every possible ordering of treatments and assigns at least one subject to each ordering….
e.g. 3 conditions –> 6 possible orderings
ABC CBA ACB BCA CAB BAC
what is partial counterbalancing?
what is the benefit?
includes only some of the possible treatment orders..
- each treatment appears equally often in each position.
- the benefit is not as many treatment orders need to be tested
e.g. treatment A appears 3 times in position 1, 2 & 3
treatment B appears 3 times in positions 1, 2, and 3
ect.
what is a within subject design?
each subject is exposed to ALL levels of the IV
also called repeated measures because participants are tested repeatedly across all conditions
(serves as a control fro yourself) more likely to find the effect of an IV because there is not as much error across groups
what are the advantages of a within subject design?
- all subject related factors are literally identical across conditions so there cannot be large individual differences to obscure the effect of the IV
- reduces error variance and leads to a more powerful design (more sensitive to the effects of the IV)
what are the disadvantages of a within subject design?
- more demanding on subjects
- there are risks of carryover effects
when would you use a within-subject design?
- when subject differences contribute heavily to variation in the DV
- when the number of subjects is limited and carryover effects are not an issue
(e.g. patients with bipolar [limited participants])
what are the two types of within-subject designs?
1) single factor two level design
2) single-factor multilevel design
within subject design:
what is a single factor two level design?
includes just 2 levels of the IV
all subjects receive both levels of the IV, but half receive the treatments in order one and half in the opposite order
within subject design:
what is a single-factor multilevel design?
a single group of students is exposed to three or more levels of a single IV
discuss the differences between a posttest-only design and a pretest-posttest design…
A posttest is an assessment measure given to participants after they have received treatment as part of a research study.
A pretest-posttest research design must provide participants with the same assessment measures before and after treatment in order to determine if any changes can be connected to the treatment.
what would you expect to find in the abstract section of a research paper?
- brief summary of paper
- the hypothesis
- the experimental method (materials, data gathering procedures)
- the findings as they relate to the hypothesis
- the conclusions / implications of findings
what would you expect to find in the introduction of the research paper?
- describes the problem under investigation
- literature review
- discusses methodology of study
- state the prediction of what they think will happen
what would you expect to find in the methods section?
what are the 4 sections in the methods section
- describes in detail how the study was conducted
- allows the reader to evaluate the procedures and replicate if they wanted to..
4 sections:
1) participants
2) Materials
3) procedure
4) design
what are the things that you would expect to find in the results section of a research paper?
- summary of the data collected
- the presented facts (they are not interpreted)
- descriptive stats
- a statement to whether the findings are statistically significant and supported the hypothesis
what would you expect to find in the discussion section of the research paper
- evaluates and interprets the results in terms of the original hypothesis
- discusses any difficulties of research
- discusses future directions / practical implications of findings
How is the References section layer out?
- alphabetical order
- indented
- double spaced
what is the appendix section used for?
- detailed description of materials
- helps the reader to understand, evaluate, and replicate the study
how is an in-text citation layed out?
(Jones, 1998)
(Jones & Charles, 1998)
(Jones et al., 1998)
how to cite a journal article in APA
- Author or authors. The surname is followed by first initials.
- Year of publication of the article (in round brackets).
- Article title.
- Journal title (in italics).
- Volume of journal (in italics).
- Issue number of journal in round brackets (no italics).
- Page range of article.
- DOI or URL
e.g.
Ruxton, C. (2016). Tea: Hydration and other health benefits. Primary Health Care, 26(8), 34-42. https://doi.org/10.7748/phc.2016.e1162
how to cite a book in APA
- Author or authors. The surname is followed by first initials.
- Year of publication of the book (in round brackets).
- Book title (in italics).
- Edition (in round brackets), if other than first.
- Publisher.
e.g.
Fletcher, D. P. (2018). Disrupters: Success strategies for women who break the mold. Entrepreneur Press.
What are factorial designs?
Two or more factors, each with two or more levels, are manipulated in a cross manner
they have more than one IV and each IV is present at every level of the other IV
What is the term factor synonymous with?
independent variable
What is the simplest factorial design?
a 2X2 between-subject factorial design
What is a 2X2 between-subject factorial design?
two factors with two levels of each IV, manipulated between subjects
What is the benefit of using a factorial design over two separate single-factor designs?
examine the effects of more than one IV, both individually and collectively, on the DV.
How many hypotheses does a 2X2 factorial design test?
3 hypotheses
What are the three hypotheses that a 2X2 factorial design tests?
- Is there a main effect of factor A?
- Is there a main effect of factor B?
- Is there an interaction between factors A and B?
What is the main effect of factorial designs?
the separate effect of each IV
What is the separate effect of each IV (main effects)?
It is the effect of each variable separately on the DV (like doing separate experiments with single IVs)
How to determine the main effects?
Compare row means collapsed across columns (main effect of Factor A)
Compare column means collapsed across rows (main effect of Factor B)
What is the interaction of factorial designs?
when the effect of one IV is different at different levels of the other IV
Can interactions be determined by performing separate single-factor studies?
No, they are unique to factorial designs
What are the three possible outcomes when analyzing a factorial experiment?
- There may or may not be a significant main effect for variable A
- There may or may not be a main effect for variable B
- There may or may not be a significant interaction between the two IV’s
What do the lines on a graph look like when an interaction may be present in a factorial design?
not parallel
What do the lines on a graph look like in a factorial design when the effect of one factor on the DV is different across the different levels of the other factor? (aka an interaction)
non-parallel lines
what is a major distinction between qualitative and quantitative methods?
Quantitative techniques use __________ while qualitative techniques involve __________
numerical descriptions; verbal descriptions
What do the lines on a graph look like in a factorial design when one factor behaves the same at each level of the other factor (indicating NO interaction)?
parallel
close ended questions
a) give a fixed number of responsive alternatives
b) are difficult to code
c) give more information than open ended questions
d) are a good way to find out what people think
a) give a fixed number of response alternatives
What is a factorial within-subjects design?
a design when each subject is exposed to every combination of levels of all the factors