Reading 7: Statistical Concepts and Market Returns-LOS b 习题 2011, frequency, highest, center, style

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Session 2: Quantitative Methods: Basic Concepts
Reading 7: Statistical Concepts and Market Returns

LOS b: Define a parameter, a sample statistic, and a frequency distribution.

 

 

Twenty students take an exam. The percentages of questions they answer correctly are ranked from lowest to highest as follows:

32	49	57	58	61
62	64	66	67	67
68	69	71	72	72
74	76	80	82	83

In a frequency distribution from 30% to 90% that is divided into six equal-sized intervals, the absolute frequency of the sixth interval is:

A) 2.

B) 3.

C) 4.

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The intervals are 30% ≤ x < 40%, 40% ≤ x < 50%, 50% ≤ x < 60%, 60% ≤ x < 70%, 70% ≤ x < 80%, and 80% ≤ x ≤ 90%. There are 3 scores in the range 80% ≤ x ≤ 90%.

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Which of the following is an example of a parameter?

A) Population variance.

B) Sample standard deviation.

C) Sample mean.

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A parameter is any descriptive measure of a population characteristic. The population variance describes a population while the sample standard deviation and sample mean are each descriptive measures of samples.

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A summary measure of a characteristic of an entire population is called a:

A) statistic.

B) parameter.

C) census.

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A parameter measures a characteristic of the underlying population.

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Which of the following statements regarding frequency distributions is least accurate? Frequency distributions:

A) organize data into overlapping groups.

B) summarize data into a relatively small number of intervals.

C) work with all types of measurement scales.

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Data in a frequency distribution must belong to only one group or interval. Intervals are mutually exclusive and non-overlapping.

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Which of the following best describes a frequency distribution? A frequency distribution is a grouping of:

A) selected data into intervals (classes) so that the number of observations in each of the non-overlapping intervals (classes) can be seen and tallied.

B) independent intervals (classes) so that they can be seen and tallied.

C) data into intervals (classes) so that the number of observations in each of the non-overlapping intervals (classes) can be seen and tallied.

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A frequency distribution is a tabular presentation of statistical data that aids the analysis of large data sets.

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Which of the following statements regarding various statistical measures is least accurate?

A) The correlation coefficient is calculated by dividing the covariance of two random variables by the product of their standard deviations.

B) The coefficient of variation is calculated by dividing the mean by the standard deviation.

C) Variance equals the sum of the squared deviations from the mean times the probability that that each outcome will occur.

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The coefficient of variation equals the standard deviation divided by the mean.