Psych 210 - Chapter 4

SD^2 = ?

(∑(X-M))^2 / N

bimodal

2 modes, most common scores

first quartile

25th percentile of data

The variance calculated on 22 scores is equal to 28.93. What is the standard deviation?

5.38 units

third quartile

75th percentile of data

Mark is looking at distance estimates of where participants think cities are located on a map. Since the estimates are given by x, y coordinates, Mark thinks he should use the mode as a measure of central tendency. What other measures of central tendency are also available? Question options: a) median and mean b) range and sum of squares c) median and outliers d) outliers and mean

A

When looking at a distribution of data with a possible outlier, it is important to keep in mind the range of all scores because an extremely high or low outlier may skew the _____of the data set. Question options: a) mean b) parameters c) sum of squares d) mode

A

Which measure of variability is the average of the squared deviations from the mean? Question options: a) variance b) range c) central tendency d) standard deviation

A

A _____ distribution has more than two modes. Question options: a) bimodal b) unimodal c) skewed d) multimodal

B

A graduate business class receives these grades on the final exam: 96, 76, 81, 87, 90, 74, 88, 95, 80, 93. What is the median test score? Question options: a) 88.0 b) 87.5 c) 84.5 d) 87.0

B

A graduate statistics class is unhappy with midterm grades. The professor will curve the grades only if the class figures out how much the curve needs to be for the mean score to equal 85. The midterm scores for class members are 72, 88, 95, 76, 69, 71, 81, 80, 73, 85. What should the curve for the class be? Question options: a) 9 points b) 6 points c) 12 points d) 2 points

B

The most common score of a distribution is referred to as the: Question options: a) median. b) mode. c) mean. d) range.

B

A comparison of the most expensive house in a neighborhood and the least expensive house in a neighborhood would involve computation of which statistic? Question options: a) standard deviation b) variance c) range d) central tendency

C

EuroTravel Agency is marketing overseas trips to college students but needs to keep in mind the average student's budget when setting their rates. In order to maximize the number of trips sold, the agency decides to market to the interquartile range of the students, based on their reported budgets. Who is in this group of students? Question options: a) students with budgets between the 25th percentile and 50th percentile of the group b) students with the highest budgets only c) students with budgets between the 25th percentile and 75th percentile of the group

C

For a data set that has been skewed due to outliers, what measure of central tendency is most accurate and should be reported? Question options: a) mode b) variance c) median d) mean

C

The number of avalanche fatalities in Colorado for the last nine seasons was reported as 7, 1, 6, 6, 7, 5, 8, 2, 3. What type of distribution do the numbers represent? Question options: a) multimodal b) nonmodal c) bimodal d) unimodal

C

These are a basketball player's number of points scored in five games: 21, 2, 15, 19, 15. Which score seems to be an outlier? Question options: a) 15 b) 19 c) 2 d) 21

C

Which of these is NOT a reason to use the interquartile range instead of the range? Question options: a) The interquartile range can help assess skew better than the range can alone. b) The range includes the smallest-to-largest observations and may be unreliable. c) The interquartile range is more likely to account for outliers. d) The interquartile range is not based on the minimum and maximum scores.

C

A comparison of the person at your university earning the highest salary, likely the university president, and the person earning the lowest, full-time salary would involve computation of which statistic? Question options: a) central tendency b) standard deviation c) variance d) range

D

The Lee family is looking to buy a house in one of two suburban areas just outside a major city, and air quality is a top priority for them. One suburb advertises the use of hybrid cars and solar panels, while the other focuses on its convenient bus routes and availability of Hummer dealerships. Is the mean or median the better measure to use for deciding which area has better air quality? (Hint: These populations are skewed.) Question options: a) median, because it is never affected by outliers b) mean, because it represents the balance of the distribution c) mean, because it is always the best measure of central tendency in any population d) median, because it is less biased by skewness being dependent on the middle score

D

The middle value in a five-number summary is the: Question options: a) 75th percentile. b) mean. c) 25th percentile.

D

The numerical summary characteristics of a population are called _____, while the numerical summary characteristics of a sample are called _____. Question options: a) statistics; sum of squares b) statistics; parameters c) parameters; variance d) parameters; statistics

D

When the mean is presented in research articles, it is most often accompanied by the _____ as a measure of variability. Question options: a) range b) variance c) interquartile range d) standard deviation

D

mean = sum of x / # scores

M = ∑X/N

sample mean symbol

M or bar X

how is the mean calculated?

add and divide by numbers added

deviation from the mean

amount that a score in a sample difffers from the mean of a sample

mean

average of a group of scores, typical score

varience

average of the squared deviations from the mean, how far a distribution varies around the mean

how to calculate third quartile?

calculate mean, highest half of data is Q3

how to calculate first quartile

calculate median, score below median are Q1

central tendency

descreptic statistic that best represents the center of the data set, the particular value that all th eother data seem to be gather around - highest points on graphs

interquartile range

distance between first and third quartiles

The range as a measure of variability is problematic because:

it relies on the most extreme scores, which could be outliers.

how to calculate the median?

line of scores from highest to lowest and count to find the middle one

range

measure of variability

median

middle score of all scores in a sample arranged in asceding order

when data is nominal you should be using what kind of central tendency?

mode

multiodal

more than 2 modes, most common scores

mode

most common score of all the scores in the sample

statistic

number based on sample taken by population

parameter

number based on whole population

variability

numerical way of describing how much spread there is in a distribution

unimodal

one mode, most common score

mean can be skewed by...

outliers

sum of all score symbol

sigma∑

standard deviation

square root of average of the squared deviations from the mean, typical amount that each score varies/deviates from the mean

Of the four types of population parameters used to describe any distribution, which parameter describes how far the observations scatter around the central value?

standard deviation

how to calculate interquartile range

subtract Q3-Q1

how to calculate range

subtract highest score from lowest score

how to calculate deviation of the mean

subtract mean from each score (X-M)

sum of squares

subtract mean from each score, square it, sum of all squared deviations (x-M)^2 / N

vairence of sample

sum of (x-mean) ^2 / # of smple

the median is also...

the 50th percentile

population mean symbol

µ

population symbol

σ^2 sigma squared

SD =

√(∑(X-M))^2 / N