Data refers to information collected through field studies or obtained from census or records.
The ordinary sequence of dealing with data is collection, analysis and presentation.
Cross-Sectional Data: Are the data collected about individuals at only one point in time without any follow up.
Longitudinal Data: Are the data collected from the same individuals at more than one point in time, either backward or forward.
Quantitative data: If data are in the form of numbers & mean & SD can be calculated from it, data are quantitative.
Examples are data of age, weight, height, blood pressure, hemoglobin level, etc.
Qualitative data: If data are in the form of groups with certain qualities & for each group No. & % are known and mean & SD cannot be calculated, data are qualitative.
Examples are males & females, urban & rural, anemic & non – anemic, etc.
Quantitative data can be converted to qualitative if it is easier to use a qualitative test of significance.
Example: Numeric hemoglobin level data can be converted to qualitative anemic and non – anemic data.
Parametric data has normal distribution but the nonparametric data has any distribution.
Nonparametric data include rank order data and Of the scale data, too high or too low.
Parameters: some measures representing the group, it can be classified
Quantitative parameters as measures of central tendency & measures of dispersion.
Qualitative parameters as Rate & Ratio.
Rate = event / total while Ratio = event / event.
What is the difference between ‘variable’ and ‘parameter’ – da capo?
One suggested answer to the question of difference between ‘variable’ and ‘parameter’ is:
A variable in mathematics is a symbol that has multiple values, in other words the value of it varies depending on conditions.
A parameter (usually t or u signifying time) is very similar to a variable in that the value also varies (but is normally defined as being within a certain area), however a parameter is a ‘link’ between two other variables.
Now, what – in medicine – is Cardiac Output, CO: a variable, i.e. the value of it varies depending on conditions (you might say!), or a parameter, i.e. ‘link’ between two other variables – CO is ‘linking’ heart rate and stroke volume. And you may ask is heart rate a parameter or a variable, stroke volume likewise. Add to this that variables evidently can be dependent or independent.