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Biostatistics 6100 > Test 2 > Flashcards

Test 2 Flashcards

1
Q

Assess the strength of linear association between variables

A

Correlation

One is not dependent on the other

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2
Q

equation that best describes linear relationship between variables. Manipulate X to see what Y does

one variable is assumed to vary linearly depending on the level of the other

A

Linear regression

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3
Q

can be (-1 - 1). the closer to 1 or -1 = a strong linear association. its the magnitude and direction

A

Correlation Coefficiant

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4
Q

How two variables move together

(-1 to 1) positive or negative

A

Corrleation

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5
Q

How two variables vary from their means

Also how two variables move together

A

Covariance

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6
Q
  1. assumes that each variable follows a normal distribution
  2. Also follow a bivariate normal distribution ( its a moultivariate distribution)
  3. both variables are continuous
A

Pearson’s Correlation Coefficient

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7
Q
  1. Does not follow a normal distribution
  2. Alternative Nonparametric measure of correlation
  3. Assess linear and non-linear association(curves)
    usually works off of ranks
A

Spearman’s

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8
Q

Y is always ______ on x

A

Dependent

x - independent
y - dependent

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9
Q

The equation of the line is completely dependent on what

A

The slope and in the y-intercept

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10
Q

What determines the values for the estimates of the slope and the y-intercept? It determines the best fit line. The sum of all the distances is what we are trying to minimize

A

Least Squares

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11
Q

what measures the expected rate of change in the dependent variable for one unit increase in the independent variable?

A

The SLOPE

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12
Q

situation in which the variance of the dependent variable is the same for all the data. The variability of BMI is the same for a person that is 5’10’’ and for a person that is 5’5’’.

A

Homoscedasticity

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13
Q

What does the null say with correlation coefficients?

A

There is no linear association N=0

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14
Q

The relationship between two variables

One is always dependent on the other

A

Simple linear regression

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15
Q

The measure of the rate of change in response variable for a unit increase in the independent variable

A

Slope in linear regression

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16
Q

What helps us estimate the mean value of y at a given value of X?

A

Population regression line - this is what we want to know so we can estimate it for the entire population

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17
Q

what method uses the equation of the line - y=a+bx - to describe the relationship between two variables

A

Regression

linear regression

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18
Q

the sampling variability - how the slope will vary from sample to sample is _____

A

standard error

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19
Q

what two values are used to calculate the std error of the slope

A

MSE and sum of squares for X

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20
Q

Which of the following statements best describes the slope parameter in a linear regression equation

A

measures the rate of change in the response variable for a unit increase in the independent variable

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21
Q

The relationship between two variables

One is always dependent on the other

A

Simple linear regression

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22
Q

Which of the following is used to test for the association between two categorical variables?

a single sample from same population and measure hair and eye color (2 variables) and test how these are associated

A

– Chi square

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23
Q

What helps us estimate the mean value of y at a given value of X?

A

Population regression line - this is what we want to know so we can estimate it for the entire population

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24
Q

Which of the following test is most appropriate for categorical data obtained from paired samples?

Before and after characteristics!! - is the proportion different on two occasions?

A

McNemar’s test

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25
Q

What test is used to measure one variable in two different populations?

depression in Males and Females

A

Homogeneity

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26
Q

what two values are used to calculate the std error of the slope

A

MSE and sum of squares for X

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27
Q

Which of the following statements best describes the slope parameter in a linear regression equation

A

measures the rate of change in the response variable for a unit increase in the independent variable

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28
Q

what is the strength of association; how reliable is the the association?

A

Degree of association

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29
Q

What is the function of the observed and expected concordance rates? did they respond the same on the same exact survey given two months apart. it the proportion of agreement between the 2 surveys. The reproducibility

A

Kappa Statistic

30
Q

What test is used when samples are obtained from two populations, a single categorical variable is measured, and interest is in determining whether the populations are the same across levels of the categorical variable?

A

Chi square test of homogeneity

31
Q

Which of the following test is most appropriate for categorical data obtained from paired samples?

A

McNemar’s test

32
Q

a 2d cross tabulation of frequencies of occurrence for two categorical variables

A

Contingency table

33
Q

what test would test whether the proportion of depression is similar in the two populations

A

Homogeneity

34
Q

what is the strength of association; how reliable is the the association?

A

Degree of association

35
Q

What is the function of the observed and expected concordance rates? did they respond the same on the same exact survey given two months apart. it the proportion of agreement between the 2 surveys. The reproducibility

A

Kappa Statistic

36
Q

a test that is done on data that is ranked and continuous and does not have to be normally distributed

A

NonParametretic test

37
Q

a two-independent sample t-test that is a function of (uses) the sample size and the ranks of the observations

A

Mann-Whitney U Test

38
Q

A test that uses the + or -. the outcome is measured in matched or paired samples

Before and after data, data is from the same person

A

Sign test

39
Q

what test always uses ranked data, is continuous and never normally distributed

A

Nonparametric test

40
Q

A test that test whether two populations are equal

2 independent samples

A

Mann-Whitney U test

41
Q

what test has a test statistic based on the counts of + and -‘s obtained from the differences in before and after scores

A

Sign test

42
Q

What test is when the null is rejected if the median difference is zero

A

Sign test

43
Q

a nonparametric test that test more than two independent samples and also test is the population medians are equal

A

Kruskal-Wallis test

44
Q

a type of sign test that is measure in matched or paired samples. does not follow a normal distribution, test statistic is W

A

Wilcoxon signed rank test

45
Q

When would you reject the null in a Kruskal-Wallis test.

A

you reject if the evidence shows that there is a difference in the median of the data among the three populations

46
Q

Most nonparametric method perform analysis using

A

rank test

47
Q

What method allows the researcher to remove the effect of the confounding variable? the one variable that might alter the true relationship between two variables (smoking/lung cancer)
confounding = drinking

A

Cochran-Mantel-Haenszel

48
Q

what method adjusts for the confounding variable. the researcher computes with the confound variable and without and then compares the two to see if it makes a difference

A

Cochran-Mantel-Haenszel

49
Q

y hat =

A

estimated regression of a line

50
Q

what is the estimate of the part of the total variability in the response that can be explained by the linear association between X and Y

A

MSregression

51
Q

How are the results from a regression analysis usually presented

A

ANOVA table

52
Q

In regression, what is referred to as the “residual?”

slide 55 in the corrleation/regression pp

A

The variance that is not explained

MSE

53
Q

In a two-factor ANOVA invovling factors A and B and their interaction, which hypothesis should be tested first

A

Interactin

54
Q

What does the F-statistic in ANOVA represent

A

The ratio of between group to within group measures of variability

55
Q

Which of the following post-hoc tests is best used when the goal is to compare each treatment with a control group

A

Dunnett’s

56
Q

In post-hoc analyses, what is the name of the test that adjusts the two-sample t-test by dividing the type I error rate by number of pairwise comparisons.

A

Bonferroni

57
Q

In the analysis of variance, the test statistic is based on which of the following distributions (statistical tables)?

A

F

58
Q

Which of the multiple comparison methods presented do not adjust (unadjusted) for inflation of the experimentwise error rate

A

Fisher’s

59
Q

The hypothesis test used in the analysis of variance involves a comparison of

A

Means of several groups

60
Q

A main goal of hypothesis testing is to?

A

Simultaneously minimize the chance of making either a type 2 or type 1 error

61
Q

What would we expect the F value to be near when the null hypothesis is true

A

1

62
Q

The error rate used to describe the overall Type 1 error rate when conducting post-hoc multiple comparison tests is called

A

Experimentwise error rate

63
Q

When visually assessing interaction between two factors in ANOVA, parallel mean profile lines are an indication of significant interaction

A

FALSE

64
Q

What statistical test measure the variability of mean between groups and also with the groups

A

ANOVA (F)

65
Q

What is the estimated variance - the measure of variability within the groups

A

MSE

66
Q

What is the total amount of variability, NOT the average

A

Sum of squares

67
Q

what is the measure of proportion of total variation that can be accounted for by the indepedent factor; it ranges from (0 and 1)

A

R2 - coefficient of determination

68
Q

what is the same as Bonferroni but has more power and controls the error rate no matter how many times you test the data

A

Tukey’s

69
Q

What compares groups means with control group means

A

Dunnett’s

70
Q

In ANOVA, when comparing means, what hypothesis test is done first

A

Interaction

Biostatistics 6100 (1 decks)

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