Chapter 8: Descriptive Statistical Analysis

Chapter 8: Descriptive Statistical Analysis

1. Types of Statistics:

• Descriptive Statistics: Used to describe and summarize data.

• Inferential Statistics: Used to draw conclusions about a population from a sample of data.

2. Measures of Central Tendency:

• Mean: Represents the central value of a dataset.

• Median: The middle value when the data is arranged in ascending order.

• Mode: The value that appears most frequently in the dataset.

3. Measures of Dispersion:

• Variance: Indicates the average squared deviation of values from the mean.

• Standard Deviation: The square root of the variance, representing the spread of values.

• Error: The difference between the actual value and the predicted value.

• Range: The difference between the largest and smallest values in the dataset.

4. Coefficient of Variation:

• Formula: 100 * S / Xtb

• Representation: Accuracy of the data, also known as RSD (Relative Standard Deviation).

5. Descriptive Statistical Analysis Tools:

• In Excel:

• DATA > DATA ANALYSIS > DESCRIPTIVE STATISTICS

• If DATA ANALYSIS is not available:

• File > Options > Add-ins > Analysis Toolpak > OK

6. Common Errors:

• “Input range contains non-numeric data”: When data contains labels but labels are not marked.

• Only the Confidence column is displayed: When “Summary statistics” is not checked.

• “Please choose at least one statistical option”: When neither “Summary” nor “Confidence” is selected.

7. Important Parameters:

• Standard error: Error of the sample.

• Confidence level: Error of the batch/population.

8. Estimating Accuracy:

• Mean (Average), STDEV: Used to estimate the accuracy of data.

• Mean (Average), STDEV: Used to estimate the %RSD value.

9. Unavailable Functions:

• Standard error, Range, Confidence level: There are no direct calculation functions in Excel.

10. Estimating Confidence Interval:

• Confidence Interval of the sample for the population: Xtb +- Standard error.

• Confidence Interval of the batch for the error: Xtb +- Confidence level.

• Alpha value: Usually used as 0.05.

• Not selecting Confidence level for Mean: Does not display the error of the batch.

• Changing alpha: Does not affect other values.

Note:

• This article provides basic knowledge about descriptive statistical analysis in Excel.

• For a deeper understanding, you need to learn more about other statistical concepts and techniques.