24 Descriptive Stats

Question 1

way of summarizing/organizing and interpreting data

Answer 1

statistics

Question 2

number from math treatment of data

Answer 2

statistic

Question 3

ex. of descriptive stats?

Answer 3

interrelationships between values, typical values, how many cases fall in particular category

Question 4

nominal and ordinal data are ___

Answer 4

discrete

Question 5

gender of patients undergoing gall bladder surgery at hospital and tabulating frequency distribution is ex. of:

Answer 5

nominal data

Question 6

taste of new food vs. conventional, count number of cases of each ordered rank of scale and then tabulate as frequency distr is example of ____

Answer 6

ordinal data

Question 7

y axis also called ____ is used to plot ____

Answer 7

ordinate; frequency

Question 8

x axis is also called ____ and used to indicate ____

Answer 8

abscissa; categories

Question 9

in interval/ration, can have increasingly accurate values depending on ___ of msmt

Answer 9

sensitivity

Question 10

useful when continuous data involves large # varied measurements

Answer 10

grouped frequency distr

Question 11

how to do grped frequency dist?

Answer 11

organize data into ordered array of score frequencies, find range of scores, decide on width, note limits of each class interval, count frequency of scores in each class interval

Question 12

how to find range?

Answer 12

highest-lowest + 1 (1 is added to include real limits of continuous data)

Question 13

how to find width?

Answer 13

range / groups

Question 14

max ___ groups

Answer 14

9 (>9 is diff. to inspect)

Question 15

if too few groups, what is prob?

Answer 15

meaning of varied data lost

Question 16

how is histogram diff from bar graph?

Answer 16

bars touch to show continuity of data

Question 17

how is frequency polygon diff from histogram?

Answer 17

plot line thru midpoint of each class interval

Question 18

why use frequency polygon?

Answer 18

allow interpolate values between points

Question 19

in positive skew, mean is ___ than the median

Answer 19

larger

Question 20

after summarize data in frequency distr, often compare _____ of diff categories

Answer 20

relative frequencies

Question 21

why find relative frequencies?

Answer 21

useful to understand trends in data on any scale

Question 22

number resulting from manipulation of raw data

Answer 22

statistic

Question 23

relative frequency of one set of frequencies to another

Answer 23

ratios

Question 24

frequency of one category relative to total sample/pop

Answer 24

proprtions

Question 25

number to make statistic more understandable

Answer 25

base

Question 26

how to calc. incidence rates?

Answer 26

new cases over time = (new cases/total pop at risk) x base

Question 27

how calc. prevalence rates?

Answer 27

total cases over time = (total cases/total pop at risk) x base

Question 28

measures of _____ are most typical or representative scores in a distr

Answer 28

central tendency

Question 29

measures of ______ are extent scores spread out

Answer 29

dispersion/variability

Question 30

for nominal data this is appropriate measure of central tendency

Answer 30

mode (most frequently occurring score)

Question 31

can be used for ordinal/interval/ratio scale data, score that divides distr in half

Answer 31

median

Question 32

x bar is used for mean for ____, mu is used for ___

Answer 32

sample; pop

Question 33

gen. most appropriate for interval or ratio data but not suitable for nominal data since no average of discrete categories:

Answer 33

mean

Question 34

for skewed continuous data, _____ may be more suitable than ___

Answer 34

median; mean

Question 35

what are 3 stats for dispersal?

Answer 35

range, variance, standard deviation

Question 36

easy to calculate; diff between highest and lowest scores–>distorted by outliers, based on extreme and not typical

Answer 36

range

Question 37

average deviation about the mean would be convenient measure of variability if solve prob by squaring deviations, called:

Answer 37

sum of squares (however, overstates spread)

Question 38

sum of squared deviations divided by # cases is called:

Answer 38

variance

Question 39

for variance for sample, use (n-1) instead of (n)…why?

Answer 39

otherwise too small estimate as lost a degree of freedom calculating x bar

Question 40

what is sq root of variance?

Answer 40

standard deviation

Question 41

what is standard error of mean?

Answer 41

when calc SD from means of several samples of pop. (SD / sq rt of n)