Unit 2 Test

Why is the median unaffected by extreme scores occurring in only one tail of the distribution? a. Because the median does not take into account the actual values of all the scores b. Because the median takes into account the actual values of all the scores c. Because the median is only one point in the whole distribution d. Because the median is based only on how frequently the median score occurs

a. Because the median does not take into account the actual value of all the scores

Of the three kinds of variances, which use(s) N-1 in the final division? a. The estimated population variance b. The sample variance c. The population variance d. All three

a. The estimated population variance

Which of the following is not communicated by a measure of variability? a. The location of the distribution b. How consistently close to the mean the scores are c. How spread out the distribution is d. The differences among the scores

a. The location of the distribution

A psychology professor wanted to describe his/her class in terms of the personality characteristic of introversion/extroversion. The population variance was estimated to be 2.56. What does this mean? a. When the professor uses the population mean to predict individuals' scores, he/she should expect to be in error by about 2.56 b. When the professor uses the population mean to predict individuals' scores, he/she should expect to be more accurate by about 2.56 c. It is impossible to tell because the mean is not known d. The sample mean differs from the population mean by about 2.56

a. When the professor uses the population mean to predict individuals' scores, he/she should expect to be in error by about 2.56

Sampling distributions of means are always a. approximately normally distributed b. positively skewed c. negatively skewed d. more variable than the population from which the samples were drawn

a. approximately normally distributed

The z-score transformation is a useful statistical tool because it enables statisticians to a. compare and interpret scores from virtually any distribution b. determine which scores are the "best" scores c. transform data by multiplying by a constant d. revise the shape of distributions to be more useful

a. compare and interpret scores from virtually any distribution

The mode is the appropriate measure of central tendency when the scale of measurement is a. nominal b. ordinal c. interval d. ratio

a. nominal

According to the central limit theorem, the sampling distribution of means always approximates a _______ distribution. a. normal b. positively skewed c. negatively skewed d. bimodal

a. normal

S sub-x squared is the symbol for a. population variance b. sample variance c. population standard deviation d. sample standard deviation

a. population variance

A sampling distribution is an approximately normal distribution a. regardless of the shape of the raw score distribution b. only when the shape of the raw score distribution is approximately normal c. only when the raw score population mean is equal to the sample mean d. regardless of the distribution of the same means

a. regardless of the raw score distribution

Measures of variability are used to a. summarize and describe the extent to which scores in a distribution differ from one another b. summarize and describe the extent to which scores in a distribution differ from the extreme scores c. make appropriate decisions regarding graph size, shape, and style d. summarize and describe measures of central tendency

a. summarize and describe the extent to which scores in a distribution differ from one another

A score's deviation conveys two pieces of information about the score's location: The number indicates _________, and the sign indicates ________. a. the score's distance from the mean; whether the score is greater or less than the mean b. whether the score is greater or less than the mean; the score's distance from the mean c. the size of the score; whether the score is a good score d. whether the score is a good score; whether the score is positive of negative

a. the score's distance from the mean; whether the score is greater or less than the mean

The proper way to describe errors of prediction is to compute a. the variance b. the range c. a z-score d. a T-score

a. the variance

To evaluate a person for possible brain damage, a neuropsychologist gives the person a visual memory test and a reading test. To compare the person's performance across these two tests, what should the neuropsychologist do? a. Graph the raw score distribution for each test on the same graph b. Calculate a z-score for each test c. Calculate z-scores for the sample means d. Find the simple frequency of the person's raw score for each test

b. Calculate a z-score for each test

A program evaluator for a large school district wants to know how much intelligence varies in the elementary schools. She randomly selects one classroom at each grade level in each elementary school and administers an intelligence test to the children in those classrooms. In order to find out which school has the most consistent intelligence level, which of the following should she calculate for each school? a. The mean b. The standard deviation c. The median d. The range

b. The standard deviation

With respect to other scores in a distribution, measures of central tendency a. are around all the other scores. b. are the points around which most of the scores are located c. usually fall in the tails or extremes of the distribution d. are never actually equal to one of the scores in the distribution

b. are the points around which most of the scores are located

Standard deviation is defined as the square root of the a. average of the deviations around the mean b. average of the squared deviations around the mean c. sum of the deviations around the mean d. sum of the squared deviations around the mean

b. average of the squared deviations around the mean

Variance is defined as the a. average of the deviations around the mean b. average of the squared deviations around the mean c. sum of the deviations around the mean, squared d. sum of the squared deviations around the mean

b. average of the squared deviations around the mean

The population mean is estimated by a. calculating the mean of as many scores as we can get from the population b. calculating the mean of a random sample drawn from the population c. calculating the mean of a sample and then transforming it to reflect the size of the population d. calculating all measures of central tendency for a random sample drawn from the population

b. calculating the mean of a random sample drawn from the population

The term variability is most opposite to a. central tendency b. consistency c. association d. homoscedasticity

b. consistency

The relative frequency(ies) obtained from the standard normal curve is (are) the _____ of the raw scores in our data, if the data formed a perfect normal distribution. a. z-scores b. expected relative frequency c. expected simple frequency d. model

b. expected relative frequency

In sampling distributions, all the samples contain sets of raw scores a. with the same variance b. from the same population c. with the same mean d. that are representative of the population mean

b. from the same population

As the N of the samples used in a sampling distribution _______, the sampling distribution becomes _______ a. decreases; more like a perfect normal curve b. increases; more like a perfect normal curve c. decreases; less spread out d. increases; more spread out

b. increases; more like a perfect normal curve

z-scores can be calculated from a. any data b. interval or ratio scores c. nominal or ordinal scores d. the range

b. interval or ratio scores

Unbiased estimators population standard deviation and variance of the population parameters will produce values that are ______ those produced by the biased estimators sample standard deviation and variance a. smaller than b. larger than c. the same as d. sometimes larger than and sometimes smaller than

b. larger than

Measures of central tendency are measures of a. distance b. location c. deviation d. extremes

b. location

When a distribution's mode > median > mean, it is said to be a. positively skewed b. negatively skewed c. symmetrical d. bimodal

b. negatively skewed

In roughly normal distributions, the standard deviation is approximately a. equivalent to the variance b. one-sixth of the range c. equivalent to the deviation of the median from the mean d. one-fifth of the absolute value of the mean

b. one-sixth of the range

When we graph the results of an experiment, the Y axis indicates the a. measure of central tendency we have used for the dependent variable b. raw score values for each subject on the dependent variable c. raw score values for each subject on the independent variable d. levels of the independent variable

b. raw score values for each subject on the dependent variable

An evaluation of where a score is located in relation to the other scores in the distribution reflects its a. absolute value b. relative standing c. standard deviation d. frequency

b. relative standing

When it is impossible to obtain all the scores in a population, the best estimate of the population mean is the a. population median b. sample mean c. sample mode d. sample median

b. sample mean

The mean is defined as a. the most frequently occurring score b. the mathematical center of the distribution c. the smallest deviation from the center score d. the point at or below which 50% of the scores fall

b. the mathematical center of the distribution

The mean of the sampling distribution always equals a. the mean of the sample, when the sample N is large b. the mean of the underlying raw score population c. 0 d. 1

b. the mean of the underlying raw score population

Which measure of central tendency is appropriate if the shape of the distribution is severely skewed? a. the mode b. the median c. the mean d. the deviation

b. the median

Which measure of central tendency should an academic counselor use to describe a student's rank order in his/her classes? a. the mean b. the median c. the mode d. the deviation

b. the median

The median is the preferred measure of central tendency when a. the scale of measurement is nominal b. the scale of measurement is ordinal c. the scale of measurement is ratio d. the distribution is symmetrical and the scale of measurement is interval or ratio

b. the scale of measurement is ordinal

Sample standard deviation and sample variance are considered biased estimates for the population standard deviation and variance because, over many calculations, they tend to be a. overestimates b. underestimates c. inaccurate in an unpredictable way d. accurate estimates

b. underestimates

The average of the deviations, Σ(X-Xbar)/N, can never actually be computed. Why? a. You cannot subtract the mean from every number in the sample b. When you subtract the mean from the some numbers, you get negative numbers c. The sum of all deviations from the mean always equals zero d. The actual N is never truly known

c. The sum of all deviations from the mean always equals zero

The variance can never be a. greater than the standard deviation b. zero c. a negative number d. greater than the mean

c. a negative number

We can use the standard normal curve as our model for a. perfectly normal distributions only b. perfectly normal distributions only, when transformed to z-scores c. any approximately normal distribution, when transformed to z-scores d. any approximately normal distribution, when transformed to percentiles

c. any approximately normal distribution, when transformed to z-scores

The quantity N-1 has a special name. It is known as the a. unbiased estimate b. biased estimate c. degrees of freedom d. freedom of variation

c. degrees of freedom

The mean of the sampling distribution of means is always a. greater than the population mean b. less than the population mean c. equal to the population mean d. the population mean divided by the square root of N

c. equal to the population mean

When deciding which type of graph (bar, line, histogram, etc.) is appropriate, we consider the characteristics of the a. variability of the distribution b. mean c. independent variable d. dependent variable

c. independent variable

Measures of central tendency indicate the _____ of a distribution; measures of variability indicate the _____ between the scores in a distribution a. similarities; differences b. mean; variance c. location; distance d. distance; location

c. location; distance

μ is the symbol for the a. population median b. population mode c. population mean d. sample mean

c. population mean

The standard deviation of the sampling distribution of means is called the a. percent of the mean b. likely error of the mean c. standard error of the mean d. special error of the mean

c. standard error of the mean

A theoretically perfect normal curve, which serves as a model of the perfect normal z-distribution, is called the a. sampling distribution of means b. standard, normalized z-distribution c. standard normal curve d. standard mean score distribution

c. standard normal curve

The standard deviation, S sub x, is a measure of how far scores deviate from a. the median b. each other c. the mean d. the most frequently occurring score

c. the mean

Which measure of central tendency is appropriate if the shape of the distribution is symmetrical and the measurement scale is interval or ratio? a. the mode b. the median c. the mean d. the deviation

c. the mean

In a skewed distribution the mathematical center is a. the median, which is the point around which most of the scores tend to be located b. the mode, which is the point around which most of the scores tend to be located c. the mean, which is not the point around which most of the scores tend to be located d. impossible to determine

c. the mean, which is not the point around which most of the scores tend to be located

Which measure of central tendency should a researcher use to describe the sex of participants in a study? a. the mean b. the median c. the mode d. the deviation

c. the mode

The proportional improvement that results from using the relationship between two variables to predict scores compared with not using the relationship to predict scores is called a. the sample variance b. the estimated population standard deviation c. the proportion of variance accounted for d. the degrees of freedom

c. the proportion of variance accounted for

The distribution of z-scores is always a. positively skewed b. negatively skewed c. the same as the distribution of raw scores d. more spread out than the distribution of raw scores

c. the same as the distribution of raw scores

The sum of the deviations around the mean always equals a. 1 b. the mean c. the sum of the total scores d. 0

d. 0

A program evaluator for a large school district wants to know how much intelligence varies in the elementary schools. She randomly selects one classroom at each grade level in each elementary school and administers an intelligence test to the children in those classrooms. If the program evaluator wants to find out which school has the highest intelligence level, which of the following should she calculate for each school? a. The variance b. The standard deviation c. The percentile d. The mean

d. The mean

When computing the variance, why do we square the deviations from the mean? a. To return the units of measure to their original form b. To compensate for the fact that the number of degrees of freedom is different from N c. To transform the raw scores into squared scores d. To compensate for the fact that deviations about the mean always sum to zero

d. To compensate for the fact that deviations about the mean always sum to zero

Which of the following is not one of the things the relative frequency of z-scores allows us to calculate for corresponding raw scores? a. Expected relative frequency b. Expected simple frequency c. Percentile rank d. Values in terms of goodness of badness

d. Values in terms of goodness or badness

In the language of statistics, when we know that a relationship exists between two variables, we can use knowledge of that relationship to a. reduce the variance b. increase the variance c. make sure the variance remains the same d. account for the variance

d. account for the variance

When deciding which type of measure of central tendency is appropriate, we consider the scale of measurement used to measure the a. variability of the distribution b. mean c. independent variable d. dependent variable

d. dependent variable

Adding a constant to or subtracting a constant from each of the scores in a distribution a. changes the value of the standard deviation by the amount of the constant b. changes the value of the standard deviation by half the amount of the constant c. changes the value of the standard deviation by 34% of the amount of the constant d. does not change the value of the standard deviation

d. does not change the value of the standard deviation

A deviation score is more informative than a raw score because it a. describes the shape of the distribution b. has a greater numeric value c. is a transformation of the raw score d. gives the score's location relative to the mean

d. gives the score's location relative to the mean

In a positively skewed distribution, the estimated population variance will be ______ than the estimated population standard deviation. In a negatively skewed distribution the estimated population variance will be _____ than the estimated population standard deviation. a. smaller; smaller b. smaller; larger c. larger; smaller d. larger; larger

d. larger; larger

The proportion of the total area under a normal curve between two z-scores corresponds to the ____ of that range of scores a. numeric magnitude b. variability c. frequency d. relative frequency

d. relative frequency

The median is defined as a. the most frequently occurring score b. the mathematical center of the distribution c. the smallest deviation from the mean d. the point at or below which 50% of the scores fall

d. the point at or below which 50% of the scores fall

In order to decide which measure of central tendency is appropriate, you must first determine a. the appropriate graph to use and the independent variable b. the independent and the dependent variables c. how the data will be collected d. the scale of measurement being used and the shape of the distribution

d. the scale of measurement being used and the shape of the distribution

The standard deviation is always a. twice as large as the variance b. half as large as the variance c. the square of the variance d. the square root of the variance

d. the square root of the variance

Sample standard deviation and sample variance are considered biased estimates for the population standard deviation and variance because a. they come from sample data b. N for the sample is less than N for the population c. they are not randomly selected d. they reflect the random variability of only N-1 scores

d. they reflect the random variability of only N-1 scores