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# Correlation

### Point Biserial Correlation

To test the effectiveness of a new studying strategy, a teacher randomly divides a sample of 8 students into tow groups, with n = 4 in each group. The students in group one receive training in the new studying strategy. Then all students are given 30 minutes to study a chapter before taking a quiz. The quiz scores for the t

### How do you conclude if there is a significant nonzero correlation in a population?

For each of the following , determine whether the sample provides enough evidence to conclude that there is a significant, nonzero correlation in the population. Use a two-tailed test with a = .05 A. A sample of n = 18 with r = -0.50 B. A sample of n = 15 with r = -0.50 C A sample of n = 30 with r = 0.375 D. A samp

### Cholesterol and Body Mass Index

Cholesterol and Body Mass Index: use the following data set below and use the cholesterol levels (x) and body mass index values (y) of the 40 women. a.Based on a scatter plot, describe the relationship between the variables. b.Find r-squared and use it to determine the value of the correlation coefficient. Is the correl

### Humanities Correlations - Democracy and Tyranny

Do you think that there is any correlation between a flourishing state of the arts and a democracy? A tyranny? This inquiry is examined.

### Which types of analysis does human service research use the most?

The researcher usually conducts one of 3 types of analysis, a statistical comparison, correlation or predictions. Each of these techniques provides a unique perception of the findings. Which technique do you think is used most often in human service research and why?

### Determine independence and find correlation

The Joint PMF of the pair of random variables (X1,X2) is given by: f(x1,x2) = (x1x2/35) + (2x1/35) + (x2/35) +(2/35) ; x1=1,2 x2= 1,2 a. Are X1 and X2 Independent? Justify b. What is the p= correlation(x1,x2) p= rho sign

### Hypothesis test: correlation coefficient

Coastal State University is conducting a study regarding the possible relationship between the cumulative grade point average and the annual income of its recent graduates. A random sample of 151 Coastal State graduates from the last five years was selected, and it was found that the sample correlation coefficient between cumul

### Sample correaltion coefficient

The number of convertibles sold at a car dealership in a month and the average monthly temperature (in degree Fahrenheit) are given in the Table below : Convertible sold, x 0 2 6 5 7 9 Average monthly temperature, y 40 48 58 62 72 79 Find the sample correlation coefficient r? Determine whether there is a positive

### Correlation ...

Does correlation equal causation? Does the strength of correlation depend on the direction? What is the meaning of a zero correlation? Explain your answers.

### Finding sample correlation coefficient

Problem: For major league baseball teams, Is there any relationship between player payroll and mean attendance? Player Payroll Mean Attendance 1000,000 in thousands X Y Anaheim 62.8 28.52 Balfimore 56.5 33.09 Boston 110.2

### Statisics - Scattered diagrams and linear correlation

The following data are based on information from Domestic affairs. Let X be the average number of employees in a group helh insurance plan, and let Y be the average administrative cost as a percentage of claims. X: 3, 7, 15, 35, 75 Y: 40, 35, 30, 25, 18 a) Make a scatter diagram and draw the line you think best fits the d

### Correlation, causation, and lurking Variables

Over the past decade, there has been a strong positive correlation between teachers salaries and prescription drug cost. a) Do you think that paying teachers more causes prescription drugs to cost more? Explain. b) What lurking variables might be causing the increase in one or both of the variables? explain.

### Scatter Diagrams and Linear Correlation

How much should a healthy shetland pony weigh? Let X be the age of the ponies in months and y be the average weight of the ponies, in kilograms. X: 3 6 12 18 24 y: 60 95 140 170 185 A} make a scatter diagram and draw the line you think best fits the data. B} would you say the correlation is low, moderate or strong? positiv

### Linear correlation coefficient

Given the following ordered data pairs (x, y), compute the value of the linear correlation coefficient r: (2,6) (3,0) (5,15) (5,5) (10,2). Give the value to 3 significant digits.

### maximum and minimum of correlation coefficient

The linear correlation coefficient, r, measures the strength of the linear relationship the variables in a set of ordered pairs (x,y). What is the maximum and minimum values for r?

### Scatter diagram and correlation coefficient

Below are the gestation days and longevity for 22 animals. a) Make a scatter chart. b) Calculate correlation coefficient and interpret it. c)Test the correlation coefficient for signficance. Clearly stating the degrees of freedom. Animal Gestation (Days) Longevity (Years) Ass 365 12

### Correlation, Causation, Independent & Dependent Variables

1. Does correlation equal causation? Does the strength of correlation depend on the direction? What is the meaning of a zero correlation? Explain your answers. 2. What is the difference between an independent and a dependent variable? Does a regression model imply causation? Why or why not? 3. How can you use correlation

### Correlation - Number of Months since Glide and Equipment Use

40. The manufacturer of Cardio Glide exercise equipment wants to study the relationship between the number of months since the glide was purchased and the length of time the equipment was used last week. See Attached a. Plot the information on a scatter diagram. Let hours of exercise be the dependent variable. Comment on

### Correlation - Amount Spent on Food and Family Size

What is the relationship between the amount spent per week on food and the size of the family? Do larger families spend more on food? A sample of 10 families in the Chicago area revealed the following figures for family size and the amount spent on food per week. See attached for table a. Compute the coefficient of correla

### Coefficient of correlation and coefficient of determination..

In your own words, describe the concept of correlation, include the coefficient of correlation (r) and the coefficient of determination (r2) in your description. Please include an example data set in your explanation. Again, Excel and MegaStat will do all the necessary calculations. Excel 2003: Tools > Data Analysis > Corre

### Positive Correlations (Research Methods)

There is a high positive correlation (0.74) between the eating of green Jello and development of cancer. What does this correlation mean? What is a possible third variable that could explain this correlation?

### Scatter Plot Correlation and Line of Best Fit: Formulating R

X:2.9 4.2 3.3 4.5 2.6 3.2 3.4 y:5.0 10.0 11.2 10.0 7.9 3.9 5.5 a) Make scatter diagram and draw line that best fits data b) Is correlation low, moderate or strong? Positive or negative? C) Verify Ex=24.1 and ex^2=85.75, ey=53.5, and Ey^2=458.31 and EXY=190.18 d) Compute

### Making Scatter Diagrams

I need to make a perfect positive linear correlation scatter diagram. Could you please outline this procedure so that I can continue to make other scatter diagrams (if that is possible) like a large but not perfect positive linear correlation, no correlation, large but not perfect negative linear correlation, small positive lin

### Correlation Between Urbanization and Alienation

Using the following sample data, tell us as much as you can about the relationship between degree of urbanization and an individual's sense of Alienation. URBANIZATION HIGH MIDDLE LOW TOTAL HIGH

### Correlation Coefficient

A study was conducted to determine if there was a relationship between the prices a non-member of a club paid for various publications and the prices that a member paid for the same publications. The data gathered is shown below. Non-member Member Price, x Price, y 58 32 42 22 46 20 3

### Test of hypothesis for correlation coefficient

Ten pairs of points yielded a correlation coefficient y of 0.79. If a=0.05, which of the following statements is correct if H 0:P=0? (Do not calculate a t-value.) Because 0.79 is greater than 0.632, the null hypothesis is rejected. Because 0.79 is greater than 0.602, the null hypothesis is not rejected. There is no corr

### Women in workforce scatterplot

If you were to draw a scatter plot of the number of women in the workforce versus the number of Christmas trees sold in the United States for each year between 1930 and the present, you would find a very strong correlation. Why do you think this would be true? Does one cause the other?

### Scatterplots Correlation for Data Analysis

Use the following situation to answer questions 14 to 18 below: A meteorologist wants to see if there is a relationship between the number of toronados that occur each year and the number of deaths attributed to the tornadoes. The data are shown for 10 recent years. The number of tornados is represented by x, and the numb

### Coefficient of correlation

If the coefficient of correlation is 0.6, the percentage of variation in the dependent variable explained by the variation in the independent variable is a. 6% b. 36% c. 60% d. any positive value e. 18%

### Correlation coefficient

Please see the attached file. 10. An agronomy study was performed to compare the yield (in kg/ha) of Sundance winter wheat and Manitou spring wheat under the same conditions. Listed below are actual yields of both varieties of wheat from nine test plot locations. Using a 5% significance level, is there statistically suffici