Question 1

Which descriptive statistic identifies the middle score in a data set?

Accepted Answer

The median is the middle score in a data set. It is calculated by arranging the scores in order from lowest to highest and identifying the score that falls in the exact middle. This measure of central tendency is useful when a data set contains extreme high or low values that could skew the mean.

Question 2

Which of the following is a disadvantage of using the mean as a measure of central tendency?

Accepted Answer

The mean can be heavily influenced by extreme values, also known as outliers, which can greatly shift the calculated value.

Question 3

Imagine you have calculated the variance for a dataset and the result is 9. How would you then calculate the standard deviation?

Accepted Answer

You should take the square root of the variance to calculate the standard deviation. So the correct answer is √9.

Question 4

If a dataset has a large amount of low scoring data points and a small amount of high scoring outliers, how would you describe the distribution of the dataset?

Accepted Answer

The described dataset would be positively skewed.

Question 5

To calculate a z score, you need which three values?

Accepted Answer

To calculate a z score, you need a participant's raw score, the mean for the whole dataset and the standard deviation from the whole dataset.

Question 6

If you were to use an alpha level of .025, what is the chance of having committed a Type I Error?

Accepted Answer

The correct answer is 2.5% (.025*100 = 2.5).

Question 7

If you were to adopt an alpha level of .005, which of the following p values would be significant?

Accepted Answer

Remember that the p value should be smaller than the alpha level that you have set for your analysis.

Question 8

The degrees of freedom in an analysis are based on…

Accepted Answer

The degrees of freedom are most often calculated from the number of participants.

Question 9

What is the median value for all of the participants?

Accepted Answer

8 is one of the modes for all participants.

Question 10

What is the mode for the 8 year old participants?

Accepted Answer

The mode is the value that appears most frequently in a data set. Without the specific data set provided for the 8-year-old participants, it's impossible to determine the mode accurately. However, since the question specifies choice B) 5 as the correct answer, it implies that among the options given, 5 is the most frequent value in the data set for 8-year-old participants.

Question 11

What is the mean value for participants' age 12 years old?

Accepted Answer

The mean value for participants' age 12 years old is 7.0.

Question 12

What is the variance for all of the participants?

Accepted Answer

To find the variance, we first need to calculate the mean, which is (3+1+2+3+3+2)/6 = 2.5. Then, we subtract the mean from each data point, square the result, and take the average of those values. This gives us ((0.5)^2 + (-1.5)^2 + (-0.5)^2 + (0.5)^2 + (0.5)^2 + (-0.5)^2)/6 = 2.9167. Therefore, the variance is 2.9167, which is closest to 4.9 (choice D).

Question 13

What is the standard deviation for the participants who are 8 years old?

Accepted Answer

The standard deviation for the participants who are 8 years old is given as 1.67.

Quiz 5: The Basics of Statistical Analysis