101.Sp08.Exam1.KEY - Psych 101, Spring 2008, Midterm 1...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Psych 101, Spring 2008, Midterm 1 Page 1 of 6 **ANSWER KEY** 1. (10 points) Estimate the correlation between the variables represented by each of the following 10 scatterplots. (Write your estimate below each scatterplot.) The correlations are (approximately): 1.0, 0.4, 0, 0, -0.8 0.8, 1.0, 0, 0, -1.0 One point for each correct answer 2. (5 points) Define the measurement scales associated with the following: A seven-point rating scale: Ordinal The level of estrogen circulating in the bloodstream: Ratio Religious affiliation: Nominal The Stanford-Binet IQ test: Interval Your grade on this exam: Ratio (raw scores) or Interval (for z scores) or Ordinal (letter grade) One point for each correct answer For the grade question, the default is Ratio unless you state which type of score you are considering 3. As part of a class project Lilly decided to try to determine whether people who studied harder were prone to caffeine addiction. She decided to ask people how much coffee they drank and how many hours they had studied the day before the midterm. Coffee: 0, 1, 2, 3, 4, 7, 8 Hours: 8, 1, 4, 2, 5, 8, 6 3a. (4 points) Plot these data in a form that best reveals the relationship between the variables. [Scatterplot of the data] 2 points for the correlation 2 points for labeling your axes correctly
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Psych 101, Spring 2008, Midterm 1 Page 2 of 6 **ANSWER KEY** 3b. (6 points) Compute the variance and standard deviation of the Coffee data. Which of these descriptive statistics is most appropriate and why? Variance: 8.95, standard deviation 3 Assuming that the data are normally distributed (and that the first score is an outlier) the appropriate measure of variation is the standard deviation because the SD has a systematic relationship to the probability density of the normal distribution. 2 points for the variance 2 points for the standard deviation 2 points for the explanation 3c. (4 points) Compute the standard error (of the mean) of the Hours data. What does this tell you? The standard error is 1.03. The standard error is an estimate of the standard deviation of the DOSM. It tells you how far your sample mean is likely to be from the population mean. 2 points for computing the standard error
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

101.Sp08.Exam1.KEY - Psych 101, Spring 2008, Midterm 1...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online