Biostatistik

Multiple Choice Questions of the modul Biostatistics at the OvGU Magdeburg

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Karten	10
Sprache	English
Kategorie	Mathematik
Stufe	Universität
Erstellt / Aktualisiert	14.06.2018 / 15.06.2018
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You have collected data for different variables in a behavioral experiment. Which steps do you perform
reasonably and in which order to detect relations between two variables?

enter the data into a data sheet
dtermine the scales of the data
present the data for individual variables in table form or graphically to detect potential errors in the data input
correct erroneous data
present the two variables of interest together graphically

1, 2, 3, 4, 5

1, 3, 2

1,5

1,4,3

none of these steps

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

1, 2, 3, 4, 5

1, 3, 2

1,5

1,4,3

none of these steps

In animal testing you have measured concentrations of corticosterone [ng/ml] for two different treatment
groups. What is a suitable presentation of the data?

scatter plot

distribution function

data points with box-plots

pie chart

histogram

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

scatter plot

distribution function

data points with box-plots

pie chart

histogram

Which diagram is (according to the opinion of the instructor) not adequate?

scatter plot for two quantitative variables

skyscrapers with antennae below a starry sky for arbitrary data structure

bar or pie charts for a nominal variable

histogram for a quantitative variable

mosaic plot for two nominal variables

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

scatter plot for two quantitative variables

skyscrapers with antennae below a starry sky for arbitrary data structure

bar or pie charts for a nominal variable

histogram for a quantitative variable

mosaic plot for two nominal variables

Which of the following statements is wrong?

The arithmetic mean lies in between the largest and the smallest observed value.

The standard deviation may be negative.

Quantiles require, at least, ordinal scale of the data.

The mode is suited for nominal data.

There is no meaningful measure of dispersion for nominal Data.

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

The arithmetic mean lies in between the largest and the smallest observed value.

The standard deviation may be negative.

Quantiles require, at least, ordinal scale of the data.

The mode is suited for nominal data.

There is no meaningful measure of dispersion for nominal Data.

Which of the following statements on statistical meausres is correct?

The median is always larger than the arithmetic mean.

The standard deviation measures the quadratic deviation from the median.

The variance is not affected by a change of the scale of measurement.

The median can also be determined for ordinal data.

The interquartile range measures the skewness of the data.

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

The median is always larger than the arithmetic mean.

The standard deviation measures the quadratic deviation from the median.

The variance is not affected by a change of the scale of measurement.

The median can also be determined for ordinal data.

The interquartile range measures the skewness of the data.

Which of the following “rules” does not hold, in general, for probabilities?

P ( Ā) = 1 − P (A) for the complementary event Ā (“A does not occur”) of A.

P (A ∪ B) = P (A) + P (B) for the occurence of, at least, one of the events A and B.

P (A ∪ B) = P (A) + P (B) − P (A ∩ B).

P (A ∩ B) = P (A) · P (B) for independent events A and B.

P (A|B) = P (A) for independent events A and B.

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

P ( Ā) = 1 − P (A) for the complementary event Ā (“A does not occur”) of A.

P (A ∪ B) = P (A) + P (B) for the occurence of, at least, one of the events A and B.

P (A ∪ B) = P (A) + P (B) − P (A ∩ B).

P (A ∩ B) = P (A) · P (B) for independent events A and B.

P (A|B) = P (A) for independent events A and B.

Let us assume for simplicity that 50 percent of all newborn children are male. Then the probability that
all three children in a family are of the same gender is equal to

0.25, because the probability of three boys and the probability of three girls are each 1/8.

0.50, because exactly two of the four possibilities (none, one, two or three boys) may be the case.

0.50, because in any case two children of the same gender must occur and the probability that the third child is of the same gender is equal to 1/2

0.66, because exactly two of the three equally likely cases (only boys, only girls or mixed) may be true.

None of the answers A - D is true.

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

0.25, because the probability of three boys and the probability of three girls are each 1/8.

0.50, because exactly two of the four possibilities (none, one, two or three boys) may be the case.

0.50, because in any case two children of the same gender must occur and the probability that the third child is of the same gender is equal to 1/2

0.66, because exactly two of the three equally likely cases (only boys, only girls or mixed) may be true.

None of the answers A - D is true.

In a behavioral experiment 40 percent of the animals does not show an averse reaction. How large is the
probability that, at least, one out of two animals shows an averse reaction?

1 − (0.4) 2 = 0.84.

(0.4) 2 = 0.16.

1 − (1 − 0.4) 2 = 0.64.

2 · 0.4 · (1 − 0.4) = 0.48.

(1 − 0.4) 2 = 0.36.

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

1 − (0.4) 2 = 0.84.

(0.4) 2 = 0.16.

1 − (1 − 0.4) 2 = 0.64.

2 · 0.4 · (1 − 0.4) = 0.48.

(1 − 0.4) 2 = 0.36.

Which “rule” does not hold, in general, for the expected value and the variance of random variables?

E(aX + b) = a · E(X) + b.

E(X + Y ) = E(X) + E(Y ).

V ar(X + Y ) = V ar(X) + V ar(Y ).

V ar(aX + b) = a^2 V ar(X).

E(X · Y ) = E(X) · E(Y ) for independent X and Y .

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

E(aX + b) = a · E(X) + b.

E(X + Y ) = E(X) + E(Y ).

V ar(X + Y ) = V ar(X) + V ar(Y ).

V ar(aX + b) = a^2 V ar(X).

E(X · Y ) = E(X) · E(Y ) for independent X and Y .

Which statement is not true for the normal distribution?

If X is normally distributed with expected value μ and variance σ^2 , then X−μ/σ is standard normal.

The probability that a normally distributed observation lies between μ − 2σ and μ + 2σ is approximately 95 percent.

If U is standard normal, then σ · U + μ is normally distributed with expected value μ and variance σ^2 .

For large samples the arithmetic mean is approximately normal (Central Limit Theorem).

For the normal distribution the median is always larger than the expected value.

Tastatur-Befehle:

= drehen,

= vor-/rückwärts,

= scrollen

If X is normally distributed with expected value μ and variance σ^2 , then X−μ/σ is standard normal.

The probability that a normally distributed observation lies between μ − 2σ and μ + 2σ is approximately 95 percent.

If U is standard normal, then σ · U + μ is normally distributed with expected value μ and variance σ^2 .

For large samples the arithmetic mean is approximately normal (Central Limit Theorem).

For the normal distribution the median is always larger than the expected value.

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