Presentation / Display of data Flashcards
What is another word for Nominal data?
Categorical
What is Nominal (Categorical) data?
categories into which observations fall, without any quantitative element, e. g. Eye colour, ABO blood group.
What is binary data?
Data where there are just TWO categories, e. g. Sex, HIV status.
What is Ordinal data?
Ordinal data have a quantitative element in the categories, but no well defined scale of measurement, e. g. The Apgar scale of condition of the new-born (from 0 to 10), Stages of cancer (I, II, III, IV).
what is Discrete numerical data?
Discrete numerical data have a well-defined numerical scale of measurement confined to whole numbers: Number of living children a woman has, Number of times a patient has been admitted to hospital.
What is Continuous numerical data ?
That is data where the observations may vary over some continuous numerical range: Age, Height, Body temperature, Blood pressure.
What is Frequencies?
How often each value occures.
How do you express Relative frequencies?
Percent
Which two ways are the most popular forms to display frequency?
Bar chart and pie chart.
How does the Pie chart work?
For the Pie chart the frequency is represented by the area i. e. the propotion of each ‘slice’ equals the relative frequency.
How does the bar chart work?
The hight of each bar represents the corresponding frequency.
Which two ways are the most popular forms to display numerical data?
Dotplots and histograms
How does a dotplot work?
Dotplot represents numeric data as dots lying on the real line with repeating entries stack upon each other
How does a Histogram work?
Histogram is a vertical bar chart. The range of data is split into disjoint regions: bins, and bars are drawn on their bases so that the areas of the bars (not heights!, in general) represent frequencies of data in each region.
What is the midpoint of classes/bins called?
class marks
How many bins should you choose?
between 6-12
What is the difference between unimodal, bimodal and multi-modal?
distribution has one, two or more distinctive peaks.
Explain what skew is
one tail is longer/heavier than another
What is Shape of distribution?
Shapes for comparison
What are outliers?
are there observations which appear to be different from the rest of the data. We might want to exclude them from the analysis.
What is the location?
How is the values of the data distributed?
If a curve is skew to the right, what does it look like?
The “top” is located to the left and the “tail” to the right
What is the mean value?
Average
What is the median value?
The middle value,
If N is odd, median = middle value.
If N is even, median = Average of two middle values.