Final Review U1 Inferential Statististics

Front

What is the empirical rule in statistics?

Back

The empirical rule states that for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, about 95% falls within two standard deviations, and about 99.7% falls within three standard deviations.

Front

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

Back

Approximately 84% of the data falls below one standard deviation above the mean.

Front

What is the formula for calculating standard deviation?

Back

Standard deviation (σ) is calculated as the square root of the variance. Variance is the average of the squared differences from the mean.

Front

If a test has a mean of 50 and a standard deviation of 5, what is the z-score for a score of 60?

Back

The z-score is calculated as (X - μ) / σ. For a score of 60, the z-score is (60 - 50) / 5 = 2.

Front

What does a z-score represent in statistics?

Back

A z-score indicates how many standard deviations an element is from the mean. A positive z-score indicates a score above the mean, while a negative z-score indicates a score below the mean.

Front

What is the significance of the 95% confidence interval in statistics?

Back

A 95% confidence interval means that if we were to take 100 different samples and compute a confidence interval for each sample, then approximately 95 of the 100 confidence intervals will contain the true population mean.

Front

How do you interpret a standard deviation of 30 in a dataset?

Back

A standard deviation of 30 indicates that the data points tend to deviate from the mean by about 30 units on average.

Front

What is the relationship between standard deviation and variance?

Back

Standard deviation is the square root of variance. Variance measures the average squared deviation from the mean, while standard deviation provides a measure of spread in the same units as the data.

Front

What is the area under the normal distribution curve?

Back

The total area under the normal distribution curve is equal to 1, representing the total probability of all outcomes.

Front

What does it mean if a score is in the 95th percentile?

Back

A score in the 95th percentile means that the score is higher than 95% of the scores in the distribution.