By Suha Tayyab
BIOSTATISTICS- Standard deviation, Variance, Skewness
Standard deviation tells us HOW CLOSE THE VALUES IN A DATA SET ARE TO THE MEAN.
- A low standard deviation indicates that the values tend to be close to the mean of the set.
- A high standard deviation indicates that the values are spread out over a wider range.
Variance
- Variance measures variability from the average or mean.
- Symbolized by σ ²
- It is calculated as the average squared deviation of each number from the mean of a data set.
Relationship between Standard deviation and Variance
Variance weighs outliers more heavily than data very near the mean due to the square. A higher variance helps you spot that more easily.
Skewness of curve
Depends upon the direction of the tail of the curve. If the curve tails towards the right side, it is a positively skewed curve. If the curve tails towards the left side, it is a negatively skewed curve.
In practice, a large volume of data is collected from experiments or researches, and to analyse and apply these functions, applications like Microsoft Excel, SPSS are used.
We will work with sample data in excel.
Before we begin, we will talk about what Microsoft Excel is.
Microsoft Excel is spreadsheet software used to organize data in rows and columns. It is used to perform various mathematical and statistical functions to the data.
Calculating SD
Calculating Variance
Calculating Skew
