## 5 Questions

What are the pros of using the mean as a measure of central tendency?

Easily put in equations & manipulated algebraically

What are the cons of using the mean as a measure of central tendency?

Influenced by extreme scores, called Outliers (especially when n is small)

What is resistance in statistics?

Resistance: a measure’s sensitivity to outlying values

How does the median handle outlying values?

The median is fairly resistant to outlying values.

How is the mode affected by outlying values?

The mode is just the most commonly occurring value.

## Study Notes

### Measures of Central Tendency

- Central tendency refers to the "middle" or "center" of a variable's distribution, described by a single score that best represents the entire distribution.
- There are three main measures of central tendency: Mean, Median, and Mode.

### The Mean

- The mean is the mathematical center or average value, also known as the "balancing point" of the distribution.
- The mean is calculated by summing all the values and dividing by the total number of values (n).
- The formula for the mean is: ̄𝑿 = (∑ 𝑿𝒊) / 𝒏 for samples, and 𝝁= 𝒏 (∑ 𝑿 𝒊 ) / 𝑵 for populations.
- The mean is easily manipulated algebraically and plays a critical role in inferential statistics, but it is influenced by extreme scores (outliers) and cannot be used for nominal or ordinal data.

### The Median

- The median is the score that divides the distribution in half, corresponding to the 50th percentile, and is often referred to as the "middle location" in a distribution.
- The median is calculated by finding the middle value when the data is arranged in order, and is more resistant to outlying values than the mean.
- The median is not easily used in equations or algebraic manipulations.

### The Mode

- The mode is the most frequently occurring value in a distribution.
- The mode is not affected by outlying values, but it is not easily used in algebraic manipulations or equations.

### Comparing Measures of Central Tendency

- Each measure of central tendency has its advantages and disadvantages, and the choice of which to use depends on the context and type of data.

### The Harmonic Mean

- The harmonic mean is another measure of central tendency, and it is used in specific contexts, such as in the relationship between the arithmetic, geometric, and harmonic means.
- The relationship between the arithmetic, geometric, and harmonic means is: 𝐻 ≤ 𝐺 ≤ 𝑥̅.

Test your understanding of calculating harmonic mean using a frequency table in statistics and probability theory. Practice finding the harmonic mean for different class intervals and frequencies.

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