Exam 2: Lectures 5-7 Flashcards

1
Q

two-sample t-test

A

used to determine whether or not means on two independent samples from a normal distribution are equal or whether they differ

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2
Q

hypotheses for two-sample t-tests

A

𝐻_0: γ€–π‘€π‘’π‘Žπ‘›γ€—_1 = γ€–π‘€π‘’π‘Žπ‘›γ€—_2
𝐻_π‘Ž: γ€–π‘€π‘’π‘Žπ‘›γ€—_1 β‰ γ€–π‘€π‘’π‘Žπ‘›γ€—_2

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3
Q

Sensitivity analysis

A

to see whether the best decision changes as one or more inputs change

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4
Q

two sample t-test info

A

If we fail to reject null hypothesis (p-value β‰₯ .05),

If we reject null hypothesis (p-value < .05),

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5
Q

what assumption does a two sample t-test have?

A

that the variances of two groups are equal in the population

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6
Q

Observational study

A

analyze data already available to us

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7
Q

Designed experiment

A

control for various factors such as age, gender, or socioeconomic status so that we can learn more precisely what is responsible for the effects we observe

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8
Q

Null hypothesis for one-way ANOVA

A

there are no differences in population means across conditions

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9
Q

Alternative hypothesis for one-way ANOVA

A

at least one of them will be different

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10
Q

what is the analysis of variance (ANOVA)

A

The procedure for analyzing difference between more than two population means

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11
Q

experimental units

A

Entities measured at each treatment level (or combination of levels)

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12
Q

In ANOVA, what is the variable of primary interest that we wish to measure?

A

dependent variable

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13
Q

post hoc test

A

run to confirm where the differences occur between groups

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14
Q

Given the 0.05 significance level, please understand hypothesis testing with a given p-value

A

If p-value < .05 , then reject the null hypothesis
If p-value >0.05, then fail to reject the null hypothesis

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15
Q

decision tree

A

enables a decision maker to view all important aspects of the problem at once: the decision alternatives, the uncertain outcomes and their probabilities, the economic consequences, and the chronological order of events

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16
Q

expected monetary value (EMV)

A

a weighted average of the possible payoffs for this decision, weighted by the probabilities of the outcomes

17
Q

what things do decision trees consist of

A

composed of nodes (circles, squares, and triangles) and branches (lines)

18
Q

decision node

A

represents a time when the decision maker makes a decision

19
Q

probability node

A

represents a time when the result of an uncertain outcome becomes known

20
Q

end node

A

indicates that the problem is completedβ€”all decisions have been made, all uncertainty has been resolved, and all payoffs and costs have been incurred

21
Q

In every regression study, a single variable that we are trying to explain or predict is..

A

the dependent variable

22
Q

simple linear regression

A

quantifies the relationship where there is a single explanatory variable

23
Q

purpose of simple linear regression

A

Evaluate the significance of independent variable in explaining the behavior of dependent variable

Predict the values of dependent variable based on the values of independent variable

24
Q

r^2

A

the percentage of variation of the dependent variable explained by the regression

25
Q

rule of thumb about r^2

A

< .10: trivial
.10 – .30: small to medium
.30 – .50: medium to large
>.50: large to very large

26
Q

Please clearly understand the interpretation of the regression coefficients for simple linear regression

A

If Y is dependent variable, and X1 through Xk are explanatory variables, then a multiple regression equation has the form:
𝛽_0 is the Y-intercept, and 𝛽1 through 𝛽k are the slopes
General Multiple Regression Equation:
Y = 𝛽_0 + 𝛽1X1i + 𝛽2X2i + … + 𝛽kXki

𝛽_0 and 𝛽s in the equation are regression coefficients
Each slope coefficient is the expected change in Y when this particular X increases by one unit and the other Xs in the equation remain constant

27
Q

cross-sectional data

A

usually data gathered from approximately the same period of time from a population

28
Q

time series data

A

involve one or more variables that are observed at several, usually equally spaced, points in time

29
Q

correlation

A

numerical summary measures that indicate the strength of linear relationships between pairs of variables (continuous variables)

30
Q

how do we test the assumption of homogeneity in variance

A

Levene’s Test of Equality of Variances
H0: γ€–πœŽβ€ β€œ γ€—_𝑋 = γ€–πœŽβ€ β€œ γ€—_π‘Œ (Two groups’ variances are equal)
H1: γ€–πœŽβ€ β€œ γ€—_𝑋≠ γ€–πœŽβ€ β€œ γ€—_π‘Œ (Two groups’ variances are unequal)

31
Q

outlier

A

observations that fall outside of the general pattern of the rest of the observations