Research methods and statistics 1 (year one) Flashcards
What is a hard science?
a science that is objective and measurable e.g chemistry
What must a scientifically sound experiment consist of?
- operational definitions
- suitable sample size
- control
What is the empirical approach?
science, evidence-based
When did Wilhelm Wundt open the first psychology lab?
1879
What is introspection?
Paying attention to and analysing your own thought processes
What is the order of the scientific method?
- observation-theory-hypothesis-research-research data
What is a theory and what must it consist of?
- general principals for outlining or understanding
- must include empirical investigation, prediction, explanation
- must be falsifiable
Who promoted falsification?
- karl popper (1934)
What does a good theory consist of?
- testable hypothesis
- guiding research and organising empirical evidence
- be supported or refuted
What is a hypothesis?
- a theory based prediction
To be scientifically testable what must a hypothesis be?
- clearly defined
- non-circular
- deal with observable phenomena
What are examples of famous studies that are not scientifically sound?
Asch (1951), Zimbardo (1971)
What are some of the methodological flaws of the Stanford prison experiment?
- researcher bias, small sample size, not representative sample, most guards were not violent, worst guard based behaviour on “cool hand luke”
What do we need to infer causation?
- correlation/co-variation
- time-order relationship (cause has to come before effect)
- eliminate other possible causes
- What is the independent groups design?
Groups that are made up of different people
- What do independent groups look at?
difference in performance between subjects
What is an independent variable?
- IV = variable we manipulate
What is a dependent variable?
- DV = variable we measure
What are some advantages to independent groups?
- no fatigue or boredom
- ## no carry over learning
What is a natural groups design
- IV not manipulated as it is already naturally occuring
What does the within groups design measure?
- repeatedly measure the same people on the same DV
- controls for individual differences
- ppts may do all conditions at the same time or different times
What does power refer to?
- the probability that you will find a statistically significant difference when it actually exists
What is error variance?
- variation caused by individual differences
- reducing error variance makes a significant result more likely
What are advantages of within-subjects designs?
- individual differences not a problem
- more powerful
- fewer ppts
- more convenient
What are the 4 levels of data?
- nominal
- ordinal
- ratio
- interval
What is nominal data?
names, categories
What is ordinal data?
data is ordered (e.g on a likert scale)
What is interval data?
data points have a similar interval between them (e.g height)
What is ratio data?
same as interval, but x has a zero value
What is qualitative research?
no set hypothesis
explores opinions, experiences etc
just from asking people e.g interviews
What is quantitative research?
numerical data analysed with maths based methods
via surveys, tasks etc
Give examples for each data level
- Nominal examples male/ female, smoker/non-smoker - Ordinal examples shoe size, position in race, subjective opinion (likert scales) - Interval examples voltage, temperature - Ratio examples (CANNOT go below 0) Height, weight, test scores
What are descriptive statistics?
- describing data
- see what data “looks like”
- looks at central tendancy and measures of dispersion
- only tells us about our sample, not population
What are inferential statistics?
- use sample to make inferences about the population
- help us reach conclusions beyond our data
- What does the statistic you use depend on?
2. What are the two main types of descriptive stats?
- data level
- distribution of data
- measures of central tendancy
- measures of dispersion
- measures of central tendancy
What are measures of central tendancy?
- this is how “most” people behave
- measures : mean, median, mode
- What is the mode?
- What is the median?
- How do you calculate the median?
- What is the mean?
- most common value or score
- mostly used with nominal data
- most common value or score
- central value in a data set ordered from lowest to highest
- mostly used with ordinal level data/ skewed data
- central value in a data set ordered from lowest to highest
- add up the two scores in the middle and divide by
2
- add up the two scores in the middle and divide by
- add up all the scores and divide by the number of values
- What does a histogram show?
- What is normal distribution?
- What is skewed data?
- the frequency of the data
- scores average around the middle, very few extreme scores
- bell-shaped curve
- median
- scores average around the middle, very few extreme scores
- mean is not central
- extreme scores affect the mean
- not normally distribution
- mean is not central
- How do we get around skewed data?
2. What is the 5% trimmed mean?
- remove extreme results
- take off 5% of scores from each end
equation = %required x no. scores
100
What is variance and standard deviation?
- average distance of scores from the mean
What are the measures of dispersion?
- range, interquartile range, variance and standard deviation
What is the range?
- difference between largest and smallest score
What is the IQ range?
- difference between middle 50% of scores
How do we calculate the IQ range?
- want to find the range of the middle 50 % of scores (second and third quartile)
- % required x no. scores
100 - answer rounded gives how many scores to take from top and bottom, which you find the range from
What is variance?
- deviation of scores from the meaan
- subtract the mean from each score, then find the average
- add up and square all scores, take them away from sum of scores squared divided by n, divided by n-1
- n = how many values there are
What is the standard deviation?
- square root of the variance
What descriptive statistics should I consider for each data level?
Nominal = frequencies/ %/ mode
Ordinal = median (+range)
Interval/ ratio skewed = median (+range)
ND = mean (+/-SD)
What data is chi-square used for and what does it assess for?
nominal data level
- association between categorical variables
what is the equation for expected frequencies?
(values taken from observed frequencies) (row total)x(column total)
N
what are p values?
evaluate how well the data in your sample supports the null hypothesis
what do high and low p values mean?
o High p value : data are likely with a true null
o Low p value : data are unlikely with a true null
at what value is the p-value said to be significant?
below .05
what is the alpha level?
level at which we accept result to be significant
what is the effect size for 2x2?
phi
what do different phi values represent?
- Φ .1 = small
- Φ .3 = medium
- Φ .5 = large
what are type 1 and type 2 errors?
- Type 1 : rejection of true null hypothesis (false positive)
- Type 2 : accepting a null hypothesis (false negative)
what is a Bonferroni correction?
- Change the alpha level to prevent type 1 errors
o Divide alpha level by number of tests that will be conducted
what is p hacking and how is it done?
: method of manipulating data to achieve significant results
Multiple analysis
Omitting other info
Controlling for variables
Analyse part way through then gather more data until a significant result is found
Changing DV
what is the null hypothesis and alternative hypothesis?
- Null hypothesis = statement of no difference
o True until there is evidence against it - Alternative hypothesis = statement of difference or association
What are one-tailed and two-tailed hypothesis?
- One tailed hypotheses = state which direction the effect will be in (e.g those that subscribe to Zoella will be more likely to choose the unhealthy snack
- Two tailed hypotheses = no direction stated
what do box plots show?
show medians, ranges, IQ ranges, skewness etc
Range = upper adjacent value – lower adjacent value
Uneven whiskers = skewness
how do you find the IQ range from a box plot?
IQ Range = upper hinge – lower hinge (whole box)
What is positive/negative skew?
- Deviation from symmetry
- Show a big difference between means, medians, and mode
- Extreme scores affecting the mean
- Positively skewed : scores greater than the mean skewing
- Negatively skewed : scores lower than the mean skewing