Untitled Deck Flashcards
What is experimental psychology?
The use of scientific methodology to measure individual responses in a controlled situation or experiment to investigate the mind and or behaviour.
What are the steps in the research process?
- Develop research question based on initial observations and generate theory and hypothesis.
- Identify IVs and DVs.
- Design study to collect data testing the theory (Between/within subjects).
- Analyse data and graph data or fit a model.
What makes a good statistical model?
Fitting the data well.
What is a population in research?
A group of individuals that we want to generalise findings or a statistical model to.
What is a sample?
A subset of the population which is studied to infer info about the larger population.
What are the steps to calculate standard deviation?
- Calculate the sum of deviations.
- Square each deviation.
- Divide by df.
- Square root these.
What does high SD mean?
High deviation…platykurtic.
What does low SD mean?
Low deviation…leptokurtic.
What is ratio data?
Absolute 0…no values below it.
What is interval data?
Continuous with no meaningful 0.
What is ordinal data?
Ranked data 1,2,3,4,5,6,7 etc.
What is nominal data?
Categorical.
What is mesokurtic?
Normal distribution - symmetrical, same median mean and mode.
What is negative skew?
Lower mean, higher mode.
What is positive skew?
Higher mean, lower mode.
What is platykurtic?
Thinner tails…lack outliers.
What is leptokurtic?
Thicker tails…too many outliers.
What is z-skew?
Skewness/std error skewness.
What is z-kurtosis?
Kurtosis/std error kurtosis.
What range do z-skew and z-kurtosis values have to fall in to be normally distributed?
Z-scores have to be within the +/-1.96 range.
What are the types of statistical tests?
Independent samples t-test and then paired samples t-test.
How to solve normality issues?
- Check for outliers and remove or manipulate them.
- Transform the data with a mathematical function.
- Use a non-parametric test.
Why do non-parametric tests not mind if data is not normally distributed?
Because they rank the data, they don’t make assumptions about distributions and are not affected by outliers.
What is variance?
An estimate of average variability (spread) of a set of data.
What are degrees of freedom?
Number of people who can choose - 1.
What are examples of normally distributed data?
Babies birthweight.
What do standard deviations mean for a normal distribution?
+/-1 sd from the mean has 68% of data.
+/- 1.96 sd from mean has 95% of data.
+/-3 sd from mean has 99.7% of data.
What is a z-score?
(your score - mean score) / standard deviation.
Standard error
- Standard deviation of sample means.
- Tells you how widely spread sample means are around the population mean.
confidence intervals
use sample mean and standard error to estimate out the range of mean values we have 95% confidence that the true population mean lies
Large confidence interval
sample mean is further away from the true mean of the population
Small confidence interval
sample mean is very close to the true mean of the population
what do error bars on plots represent
- 95% confidence intervals
- or standard error of the mean
test statistic
variance explained by the model/variance not explained by the model
effect/error
how to calculate a t-test
difference in means/standard error
=
explained variance/unexplained variance