Describing Data

What is standard deviation?

• The difference between the highest and lowest scores in a dataset.

• The average value of all scores in a dataset.

• The deviation or difference from the mean for a group as a whole.

• The sum of all squared deviations from the mean.

Why bother calculating the standard deviation after obtaining the variance?

• Because variance is always zero.

• Because it provides a more useful measure since it is converted into the same units as the data you are studying.

• Because standard deviation is always larger than variance.

• Because variance cannot be used in statistical analysis.

Why are descriptive statistics important?

• They predict future outcomes with accuracy.

• They explain why data occurs.

• They describe and organize data.

• They eliminate the need for inferential statistics.

Describe what the mean mathematically means.

• Mean is the most frequently occurring score in a dataset.

• Mean is the middle value when scores are ordered.

• Mean is the difference between the highest and lowest values.

• Mean is the sum of data divided by N.

Why is the range a poor measure of variability?

• Because it is always equal to zero.

• Because it is always less than the standard deviation.

• Because it includes only the two most extreme numbers, which can make it seem like there is far more variation than there actually is.

• Because it includes only the two most middle numbers, which can make it seem like there is far more variation than there actually is.

Which of these graphs show a negative skew?

• 1

• 2

What is the mean of the following set of numbers: 8, 12, 15, 10, 5?

• 10

• 12

• 8

• 15

Which of the following is not a measure of central tendency?

• Mean

• Median

• Mode

• Range

Given the heights (in cm) of 6 plants: 15, 20, 25, 30, 35, 40 what is the range of their heights?

• 25

• 30

• 20

• 15

What is the definition of Median?

• Most frequent number

• The number in the middle of an ordered list

• Max - Min

• Average of the numbers