Homework 10

# Homework 10 - Homework Assignment 10  NOT GRADED

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Homework Assignment 10  NOT GRADED  Answers will be available Friday           Psychology 60  Spring 2010  1. What information does the sign of the Pearson correlation provide? How does this  information relate to the sign of the slope (b) and will they always correspond?     2. Calculate the sum of products (SP) for the following set of scores:  X   2  6  1  3  Y  4  3  8  5  3. Assuming that you are running a two‐tailed test with alpha = 0.05, how large of a correlation  is needed to be statistically significant or each of the following samples?  a. A sample of n = 10  b. A sample of n = 20  c. A sample of n = 30    4. The regression equation is intended to be the best fitting straight line for a set of data. What  is the criterion for “best fitting” ?    ˆ 5. For the following scores, find the best fitting line, and find the predicted values of Y ( Yi ) at  each X score (that is, what values the fitted line predicts for each observed value of X)    X  Y  3  0  8  10  7  8  5  3  7  7  6  8    6. A set of n = 20 pairs of scores (X and Y values) has SSx = 25, SSY = 16, and SP = 12.50. If the  mean for the X values is  X = 6  and the mean for the Y values is  Y = 4   a. Find the best fitting line for these data  b. Calculate the Pearson correlation for the scores  c. Assuming everything else stays the same, does the value of the Pearson correlation  coefficient change if the mean for the X values is now  X = 600  and the mean for the Y  values is  Y = 400 ? Why or why not?  d. Assuming these data represent a sample from some population, do we have evidence  that there is a linear relationship in the population from which the sample is drawn?   ...
View Full Document

## This note was uploaded on 10/16/2011 for the course PSYCH 60 taught by Professor Parris during the Spring '11 term at UCSD.

Ask a homework question - tutors are online