Data Flashcards
Why screen data?
Detect blunders
Locate outliers
Discover distributional properties
Missing values
How to screen data?
Small data set: look at data
Large data set: frequency table or histogram
What are the two types of variable?
Qualitative
Quantitative
What are the two categories of qualitative variables?
Nominal: male/ female, smoker/non-smoker
Ordinal: pain (mild/ moderate/ sever)
What way is quantitative data handled?
In intervals
E.G height - 0-5, 5-10, 10-15
How to present categorical variables?
Tables of frequencies/ relative frequencies
Graphically is bar charts
If the data is symmetrical what points should be used?
Mean and standard deviation
If the data set is skewed, what data points should be used?
The median and inter-quartile range
How are interval scale variables graphically displayed?
Histograms and box plots
What are summary statistics?
They attempt to capture a typical value (the location) or the spread (dispersion)
What do you use when looking for location using summary statistics?
Mean and median
What do you use when looking for the spread/ dispersion of data when using summary statistics?
Range, inter-quartile range, variance
What is standard deviation?
The square root of variance
What is the definition of the co-efficient of variation?
C = (s/x) x 100
S - standard deviation
X - mean
A measure of variation which is independent of the unit of measurement. Can be used to compare the variation of variables measured on different scales
