HLTC22H3 Lecture : march 13 lec.docx

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limecrab194

27 Apr 2012

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If have super extreme cases then would rather use median: eg income. Variance is a measure of spread/dispersion: how does our distribution vary from the mean. If take 10 points off of each number, the mean also goes down by 10: the variance stays the same. Variable is a way of characterizing our data: eg age. Covariance: eg how is age relating to whether someone got the flu this winter. Correlation: indicates strength and direction of linear relationship btw two variables. Smoking and lung capacity slide: each row represents a different person, these two variables co-vary in the opposite direction, the more you smoke the lower your lung capacity, slide with cross. Eg when smoking variable above the mean, lung capacity below the mean. Numerators for covariance and correlation are the same. Different temporal aspects when talking about how you would describe your health. How would you describe your health: poor, fair, good, very good, excellent (likert scale, exam question.

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Dependent, independent variables; positive and inverse relationships: Consider the following statements, and indicate which variable is an independent variable and which variable is a dependent variable; moreover, determine whether there is a positive or a negative relationship between two variables. (a) - As research shows, anti-smoking campaigns reduce the number of smokers in the country. Number of anti-smoking campaigns is the _________________ variable; Number of smokers is the _______________ variable. The relationship between anti-smoking campaigns and the number of smokers is __________. (b) - More educated employees typically have higher income than less educated employees. Education is the ________________ variable; Income is the_______________ variable. The relationship between education and income is______________.

1. (Problem 2) Why is the relation between genotype and phenotype frequently complex for quantitative characteristics?

Multiple genes are involved.
The alleles are usually recessive.
The environment often influences the phenotype.
Answers A and B are both correct.
Answers A and C are both correct.

2. (Problem 6) How is the standard deviation related to the variance?

The standard deviation is the difference between the mean and the variance.
The standard deviation is the square of the variance.
The standard deviation is the square root of the variance.
The standard deviation is the square root of the difference between the mean and the variance.
The standard deviation is the square of the difference between the mean and the variance.

3. (Problem 7) What information does the correlation coefficient provide about the association between two variables?

How strongly two variables are associated
The difference in the mean values of two variables
The magnitude of the difference between two variables
The difference in standard deviation between two variables
The extent to which each variable deviates from its mean

4. (Problem 10) Narrow-sense heritability is due to what type of genetic variance?

Additive
Environmental
Genic interaction
Dominance
Genetic by environment interaction

pearcat127

Identify the true statements about the correlation coefficient, r.

a.) The correlation coefficient is not affected by outliers.

b.)The value of r ranges from negative one to positive one.

c.) When the data points in a scatter plot fall closely around a straight line that is either increasing or decreasing, the correlation between the two variables is strong.

d.) A correlation coefficient of zero means that no relationship exists between the two variables.

e.) If two variables are positively correlated, when one variable increases, the other variable decreases.

f.) The sign of r describes the direction of the association between two variables.

bluefly693

HLTC22H3 Lecture : march 13 lec.docx

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