Statistics: Variability and Standard Deviation

Flashcards covering key concepts related to variability, standard deviation, and their calculations as discussed in the lecture.

What does variability refer to in statistics?

The degree to which scores differ from each other.

What is standard deviation?

A measure of the average distance of scores from the mean in a dataset.

What is the formula for calculating the deviation score?

d = x - x̄, where x is the score and x̄ is the mean.

What is variance in relation to standard deviation?

Variance is the average of the squared distances from the mean, while standard deviation is the square root of the variance.

Why is using the range not reliable for measuring variability?

The range only considers the two extreme data points and does not summarize the overall distribution.

What is the average absolute deviation?

A measure of variability that calculates the average distance of scores from the mean, but is less preferred than standard deviation.

What adjustment do we make when calculating standard deviation for a sample versus a population?

We divide by n-1 (degrees of freedom) for the sample to avoid bias.

What percentage of data falls within one standard deviation of the mean in a normal distribution?

Approximately 68%.

What is the sum of squares?

The total of squared deviation scores, representing the total variability in the dataset.

What happens to the standard deviation if outliers are removed from data?

The standard deviation decreases because there is less variability.