__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

**into: **

__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.**

## People reacted to this story.

Show comments Hide commentsVery valuable lecture, focused and easy to understand

Thank you so much Dr.Adel

Thank you Dr Maha. Your opinion reflects your broad mind and scientific personality and is very important for me. I hope I will always be at the level of your thought about me. Thanks again

A useful and valuable lecture, thanks for the knowledge and science that you publish,,

Hi Sana how are you I hope every thing is ok with you. Thanks for your valuable comment and if you regularly access my blog you will find a new article or a workshop session published every 3 days. I hope it will be useful and if you have any question don’t hesitate to contact me