Smokers are 29 times more likely to die from lung cancer than non-smokers, and heavy smokers are 90 times more likely to die from lung cancer. And people who smoked and then quit, their risk was cut in half. As a result, we can conclude that the more smoking, the higher risk of lung cancer, and quitting smoking can reduce that risk. 

Dose-response effect Example

If substance A leads to biological reaction B, then in general (but not 100%), a larger dose of A leads to the stronger reaction B. 


University of Michigan - Ann Arbor

Quantitative data is referred to as Continuous or Discrete data because it comprised of numerical data. This data is commonly stored in data types of Integer, Float, and Double. When using Quantitative data for Statistical learning it is often used in regression problems to predict a numerical output such as percent increase or decrease. This data is a an objective measurement.

Quantitative Data 

An observational study, as supposed to an experimental study is a type of study that investigators observe the effect of an intervention without assigning it to the subjects at random.  That is, the subjects choose their own treatment/ intervention.  

Observational studies may prove to be less costly that RCT's, given that the investigator need not actively change the behavior of the subjects


Observational Studies

Pearl, J., & Mackenzie, D. (2018). $$\mathit{The \ Book \ of \ Why: \ The \ New \ Science \ of \ Cause \ and \ Effect.}$$ Basic Books.

The Book of Why

Often times, statistical methods rely on measuring the distance between quantitative data points. However, there are various ways to measure this distance. These include:

1. Euclidean distance 
2. Manhattan distance
3. Hamming Distance

Measuring Distance Between Quantitative Data Points

Here is a video on the differences between discrete and continuous data.

[MooMoo Math and Science]. (2017, March 24). Continuous vs Discrete Data [Video File]. Retrieved from [www.youtube.com/watch?v=g30cI4Kbhb4](https://www.youtube.com/watch?v=g30cI4Kbhb4) 

Continuous vs Discrete Data (Reference)

The case of quantitative analysis of quantitative data applies when we use numeric data to analyze the data statistically and mathematically.  

Quantitative Analysis of Quantitative Data

The case of quantitative analysis of qualitative data applies when we use qualitative data to analyze the data statistically and mathematically.  


Quantitative Analysis of Qualitative Data

The case of qualitative analysis of quantitative data applies when we use quantitative data to interpret (qualitatively analyze) the data.  It can involve searching for patterns in the data to understand the "meaning."  

Qualitative Analysis of Quantitative Data

Types of Quantitative Data

A cohort study is conducted to observe multiple groups of people over a period of time for comparison to see the potential effect of a phenomenon (possible influential factor) that the investigators are interested in.  The cohort studies are done either prospectively or retrospectively.  

Cohort Studies

Case-control studies are observational studies where subjects' previous experiences are used as evidence to assess how those who had experience with the specified condition varied from those who did not and why.

Case-control studies

-Observational studies can be conducted in the natural habitat of the target population as opposed to an artificial, controlled setting in laboratory
-Observational studies maintain "purity" in that there are few issues of ethics or feasibility due to no need for intervention being applied. For example, if investigating smokers and health, we cannot make non-smokers start smoking for the experiment, but we can find people who are already smokers. 

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