Intro to statistics Flashcards
What are the 2 main types of data?
Nominal (qualitative)
Ordinal (quantitative)
What are the 2 types of Nominal/qualitative data? give examples
Unordered (e.g. male/female)
Ordered (e.g. small, medium, large)
What are the 2 types of ordinal/quantitative data? give examples
Discrete/whole numbers (e.g. students on the course, children in the family)
Continuous (e.g. weight in kg)
When analysing ordinal data, what are the 2 ways in which it can be analysed?
can be analysed by both, parametric or non-parametric tests
When would parametric and non-parametric tests be used to analyse data?
If the distribution is normal – use parametric test;
If the distribution is skewed – use a non-parametric test
Give Examples of non-parametric tests
Mann-Whitney, Wilcoxon, Kruskal-Wallis
Give Examples of Parametric tests
t-tests and Anova
What test is used to determine if there is a significant association between the two categorical variables(e.g., male/female voters vs voting preference (Labour, Conservative) ?
Chi2 (squared)
Define skewed distribution of data
Skewed distributions are asymmetrical and have data that clusters toward one end
How is normal distribution of data displayed ?
represents the distribution of many random variables as a symmetrical bell-shaped graph.
Define qualitative data
method of observation to gather non-numerical data.
Define quantitative data
measures of values or counts and are expressed as numbers
Define mean
the sum of all the samples, divided by the number of samples (n).
Define median
the value halfway through the ordered data set, below and above which there lies an equal number of data values.
Define quartile
Lower (first) quartile chosen to place 25% of the data below it, 75% above it
Upper (third) quartile chosen to place 75% of the data below it, 25% -above it
Define IQR
IQR (Third Quartile minus First Quartile) quantifies the spread or dispersion of the sample
Q3 - Q1
Define Confidence Interval
The CI is a range of values, above and below a finding, in which the actual value is likely to fall.
Define p-value
p value - indicates how likely it is that a result occurred by chance alone
Define effect size
way of quantifying the difference between two data groups
What does p = 0.05 mean?
95% sure that difference between data sets is real
What’s the difference between statistical and clinical significance?
If a result is statistically significant it means it was unlikely to have occurred by chance.
If it is clinically significant, then it reflects its importance on clinical practice
when should t-test be used?
When we want to compare the means of two sets of scores
Difference between paired and unpaired t-test data?
Paired: eechnumber in group 1 is linked to a number in group 2 and the difference between each pair is investigated
Difference between paired and unpaired t-test data?
Paired: each number in group 1 is linked to a number in group 2 and the difference between each pair is investigated
Unpaired: numbers one each group are unrelated to each other