Sections 1 & 2
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| What are natural numbers? | Positive numbers (+) that have any actual value from zero (0) to infinity (
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| What is the general rule of operations when working with a grouping of numbers with no symbols of grouping involved? | Multiply and/or divide from left to right, before adding and/or subtracting from left to right.
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| What are signed numbers? | Those values that are positive (+) and those values that are negative (–).
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| How do you add two numbers with different signs? | Subtract the smaller from the larger and give the answer the sign of the larger value.
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| What is the result when one negative number is divided by another negative number? | Positive.
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| What is a good rule to follow when rounding? | Round only the final answer; do not round intermediate totals leading to the final answer.
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| Round the following numbers to the nearest whole number: a. 7.43. b. 8.64. c. 17.77. | a.7.
b. 9.
c. 18.
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| 8. Round the following numbers to the nearest tenth: a. 3.173. b. 7.428. c. 2.65. | a. 3.2. b. 7.4. c. 2.7.
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| Round the following numbers to the nearest hundredth: a. 8.121. b. 6.7379. c. 3.415. | a. 8.12. b. 6.74. c. 3.42.
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| Write this phrase as a mathematical expression: “The square root of 16 is 4.” | 16
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| How is the rate determined? | Divide the portion by the base to get a decimal. Then change this decimal into the percent form.
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| How is the portion determined? | Multiply the base (B) times the decimal equivalent of the rate (R).
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| How is the base determined? |
Change the rate to a decimal and divide the portion by this decimal.
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| What statistical method is considered an objective approach? Subjective approach? | Descriptive. Inferential.
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| Which of the following are variables: 3, A, 4.5, +, Y? | A,Y.
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| In the function M=F(N), which one is the independent variable? The dependent variable? | N,M.
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| What are subscripts used for? | To denote the different individual values in a set of data, to indicate which set of data a certain measure represents, and to denote the different individual points in a series, etc.
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| What is the meaning of the symbol []? |
The summation sign,
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| What do you call data that can be expressed only in whole number units? | Measures that characterize a population.
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| What is the meaning of the term “population” as used in statistical language? | A part of a population.
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| Define parameters. | Measures that characterize a population.
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| What is a sample? | A part of a population.
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| What is a random sample? | A sample where each item in the population has an equal chance of being included in the sample chosen.
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| Define stratified sampling. |
Dividing the population into subgroups (strata) in such a way that there is as great a homogeneity as possible within each stratum and as great a heterogeneity as possible between each stratum.
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| Explain the difference between purposeful and unintentional bias. | Unintentional—bias which occurs as a result of insufficient planning.
Purposeful—collecting or rejecting certain data based on established, such as specific temperature ranges, skill levels, time periods, and so forth.
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| Name two measurement scales that are truly quantitative. | (1) Interval. (2) Ratio.
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| Name one measurement scale that is truly nonquantitative. | Nominal.
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| What is the function of a frequency distribution? | Summarize data and describe variation in performance.
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| What is the first step in making a frequency distribution? | Determine the range of the data.
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| What is the recommended number of classes in a frequency distribution? | 10 to 20.
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| What happens to a frequency distribution if the class interval is too small? | You lose smoothness and simplicity and are left with a ragged distribution.
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| Explain cumulative frequency distribution. | Displays the number of values falling above or below a certain point on the measurement scale.
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| How are percentage frequencies determined? | By dividing the individual class frequency by the total frequencies involved.
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| What are histograms based on? | The assumption that individual values falling within each interval are evenly distributed over the interval.
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| Where are the frequencies of the class intervals plotted when constructing a frequency polygon? | With the corresponding midpoints.
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| Which graphic representation gives a better idea of the general shape of a distribution? | Frequency polygons.
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| Define the mode. | The most frequently occurring value in a distribution.
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| List the five characteristics of the mode. |
(1) It is the most typical value.
(2) It is not affected by extreme values.
(3) It is simple to estimate.
(4) It is very unstable.
(5) It is the most appropriate measure that can be used with data from a nominal scale.
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| How is the mode estimated from ungrouped data? | By finding the value that occurs most frequently.
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| How can you estimate the mode from a frequency distribution? | By finding the class with the highest frequency.
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| How can you estimate the mode from a histogram? | By drawing a line perpendicular to the baseline from the point where the dotted lines cross.
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| Define the median. | The center value in a distribution with half of the individual values on either side.
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| When should you use the arithmetic mean? | When you wish to place equal emphasize on each value in the data distribution.
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| What is the mathematical definition of the arithmetic mean? | That point in a data distribution about which the sum of the deviations equals zero.
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| What is the harmonic mean primarily used for? | Averaging rates, particularly rates of time.
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| How is weight calculated when using the weighted arithmetic means? | By multiplying an item’s value in the series by its appropriate quantity factor.
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| When would a harmonic mean be considered useless? | If zeros are present in the series.
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| Define standard deviation in mathematical terms. | The square root of the squares of all the deviations from the mean.
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| In the equations for calculating the standard deviation, what step gets rid of the negative values? | Squaring the deviations.
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| In a population, if all the values are zero, what is the standard deviation? | Zero.
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| How are the standard deviation and the variance related? | The standard deviation is the square root of the variance.
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| In a normal distribution, as n grows smaller, what happens to s? | It becomes less representative of the population.
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| Define the sampling distribution of the mean. | A theoretical frequency distribution of mean values.
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| The variability of the X values in the sampling distribution of means is affected by what two factors? | The variability of the population from which the random samples were drawn and the random sample size.
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| Define the standard error of the mean. | The standard deviation of a sampling distribution of means that is equal to the standard deviation of the population divided by the square root of the sample size.
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| The standard error of the mean measures the amount of error between a sample mean and what? | The true population mean.
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| The normal distribution is composed of what two parameters? | (1) The mean.
(2) The standard deviation.
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| Like all continuous distributions, the total area under the curve is what percentage? | 100 percent.
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| For normality testing, what is the first step in plotting data? | Arrange the data in an array from the lowest to the highest value.
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| What is a good method to learn to recognize normal data distributions? | Plot data known to be skewed and compare its line with normal data, which forms a straight line.
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| What percentage of individual items are located within a distance of one standard deviation from the mean in a normal distribution? | 68.26 percent.
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| What does the Z score represent? | How many standard deviations a value is from the mean.
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| What is a symmetrical curve? | All curves that have right and left halves alike, with respect to the center.
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| What is a nonsymmetrical curve? | A curve that has its right half shaped differently from its left half.
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| What type of curve is very common when portraying the distribution of maintenance data? | Positive skew.
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| What is the value of 5 ÷ 2 × 6? | 15
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| Compute the difference of the signed numbers –17 – (–10). | -7.0
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| Eighty is 40 percent of what number? | 200
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| What statistical method uses only a sample of data? | Inferential
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| Which action would require the use of the descriptive statistics method? | Summarize a large amount of data
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| In the equation Y=X+2, what does the symbol “Y” represent? | Variable
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| What is the value of 43? | 64
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| Which is the best example of a population in statistical language? | Total T-38s failures across the Air Force.
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| A sample of a population that is taken in such a manner that each value has an equal chance of being selected is referred to as a | Random sample
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| What are measures, such as the mean or median, called if they are computed from a sample? | Statistics
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| Which measurement scale consists of equal intervals between scale values and an arbitrary zero point? | Interval
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| The second step in making a frequency distribution is to | Determine the class interval size.
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| Given the following noncumulative frequency distribution, which class interval will give you 18 classes? | 0.2
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| If you construct a frequency distribution and the class interval is too large, the result is | A loss of detail.
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| When constructing a frequency polygon, what are plotted against the corresponding midpoints? | Frequencies of the various class intervals.
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| Which graphical method gives the best representation of the number of individual values in each class? | Histogram.
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| What measure of central tendency is the most typical value in a distribution? | Mode.
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| What is the mode of a sample consisting of these values: 6, 9, 10, 3, 2, 6, and 25? | 6.
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| The median cannot be used with data from which measurement scale? | Nominal.
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| Analysts frequently use the median because it is easy to compute and gives a better picture of data than the mean and mode when data are | skewed.
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| What must you do first to determine the median from ungrouped data? | Array the data in ascending order.
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| A true characteristic of the arithmetic mean is it is | affected by extreme values.
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| What is the arithmetic mean of the values 8, 10, 11, 11, and 5? | 9.
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| Compute a weighted mean for a distribution containing two values of 3 each, four values of 2 each, and four values of 5 each. | 3.4.
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| For any distribution, the sum of the deviations is | zero.
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| For a standard deviation of a population, if the number of values increases, the standard deviation | increases.
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| In a sample, you have 10 X-values, and each value is equal to 7. What is the standard deviation of the sample? Formula for standard deviation: | 0.
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| As the number of values in a normal distribution sample decreases, the standard deviation | becomes less representative of the population.
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| Given a large number of random samples, how is the mean of all the sample means related to the population mean? | It is the same.
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| A normal distribution contains what two parameters? | Mean and standard deviation.
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| In a normal distribution, 99 percent of the area under the normal area curve is contained within how many standard deviations on each side of the mean? | 3.
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| When plotted on normal probability graph paper, data from a normal distribution shows up as a | straight line.
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| How many standard deviations are represented by a value of 22 if X = 14 and s = 5? | 1.6.
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| If X equals 24 and s equals 6, what are the values of X ± 2s? | 12 and 36.
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| The variable that measures how many standard deviations a value is from the mean is the | Z score.
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| Where does the most frequent value of a normal curve occur? | At the center of the distribution.
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