A computer while calculating correlation coefficient between two variables X and Y from 25 pairs of observations obtained the following results: n = 25, ΣΧ = 125, ΣΧ2 = 650, ΣΥ2 = 460, ΣῪ = 100, EXY = 508 • If was, however, later discovered at the time of checking that he had copied down two pairs as X Y while the correct values were X Y Obtain the correct value of correlation . 6 14 8 12 9 6 6 8 coefficient.

An insurance investigator has observed that people with some astrological signs tend to be safer drivers than people with other signs. Using insurance records, the investigator classified 150 people according to their astrological signs and whether or not they were involved in a car accident during the previous 12 months. Do the following data indicate a significant relationship between sign and accidents? Test with a = .05.                     Libra Leo Gemini     Accident 7 4 19     No Accident 73 46 1

A sample of 30 ordered pairs produces a linear correlation coefficient of r-0.026 Which of the following statements would be true? No regression line could be calculated from these ordered pairs Although no linear correlation exists, there might be a strong non-linear correlation A negative linear correlation exists A positive linear correlation exists The regression line would not pass through the point (x, y)

Match the following sample correlation coefficients with the explanation of what that correlation coefficient means. Type the correct letter in each box. 1. r= 1 2. r = -1 3. r=-.15 4. r = .1 A. a weak positive relationship between x and y B. a weak negative relationship between x and y C. a perfect negative relationship between x and y D. a perfect positive relationship between x and y

1. The first of two samples consists of 23 pairs and gives a correlation of 0-5 while the second of 21 pairs has a correlation of 0-8. Are these values significantly different?

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