Research Lec 4

Question 1

Descriptive statistics

Answer 1

methods for organizing and summarizing data

using tables and graphs

organize and simply to get a general overview of the results

Question 2

descriptive values for population vs sample

Answer 2

parameter
statistic

Question 3

know parameter vs statistic symbols

Answer 3

population - greek letters
statisitc - normal

Question 4

frequency distribution

Answer 4

shows where each individual is located relative to others in the distribution

Question 5

grouped frequency distribution

Answer 5

used when a set of scores covers a wide range of values

Question 6

how are frequency distributions typically graphed?

Answer 6

histograms

Question 7

when should you use a smooth curve?

Answer 7

when its interval or ratio data and a large N

note: emphasizes the fact that the distribution is not showing the exact frequency for each category

Question 8

how many scores are within 1 SD of the mean on a normal distribution curve?

Answer 8

34%

34 for above and 34 for below

Question 9

how many scores are 2 SD away from the mean on a normal distribution curve?

Answer 9

13.5%

Question 10

how many scores are 3 SD away from the mean on a normal distribution curve?

Answer 10

2.35%

Question 11

% within 1SD, 2SD, 3SD of the mean (both above and below)

Answer 11

1SD: 68%
2SD: 95%
3SD: 99.7%

Question 12

z scores

Answer 12

how many standard deviations a data point is from the mean of a distribution.

Question 13

skewed vs normal distribution

Answer 13

you want symmetrical

skewed - scores pile up on one side and leave extreme values as a tail

Question 14

positive skew

Answer 14

scores bunched at low values with the tail pointing to the high values

Question 15

negative skew

Answer 15

scores bunched at the high values with the tail pointing to the low values

Question 16

kurtosis

Answer 16

the “peakedness” of the distribution

Question 17

leptokurtic

Answer 17

higher/thinner peak

lipo suction

Question 18

platykurtic

Answer 18

lower/broader peak

Question 19

normality test

Answer 19

used to determine whether a sample was taken from a normally distributed population

Question 20

stem and leaf plot

Answer 20

frequency distribution

stem consist of the first digit and the leaf consists of the final digits

2 I 0 2 4 5 5
3 I 1 2
4 I 9

Question 21

central tendency

Answer 21

describes the center of the distribution and represent the entire distribution of scores as a single number

mean, median and mode

Question 22

mode is appropriate for what kinds of data

Answer 22

nominal, ordinal, interval or ratio

Question 23

median

Answer 23

50% of the scores have values that are equal to or less than the mean

Question 24

mean is appropriate for what kinds of data

Answer 24

most commonly used
-interval and ratio

Question 25

one advantage of the median is

Answer 25

unaffected by outliers

Question 26

mean is used with what kind of data

Answer 26

must be interval or ratio

Question 27

mean median mode - which is most common

Answer 27

mean

Question 28

T/F: modifying a distribution by disgarding score or by adding new scores will usually change the value of the mean

Answer 28

T

Question 29

if your mean is affected by extreme scores, what should you do

Answer 29

dont report it, use median or mode bc the mean will not provide a central value

Question 30

in symmetrical data, the ___ and ___ will always be equal

Answer 30

mean and median

Question 31

in skewed data, where will the mean, median and mode be?

Answer 31

mode will be at the peak, mean will be towards the tail, median will be between the mean and the mode (mode is where the most scores are - at the peak and this is why is skewed)

Question 32

APA sample and population mean symbol

Answer 32

M

Question 33

APA SD symbol

Answer 33

SD

Question 34

what usually accompanies a measure of central tendency?

Answer 34

a measure of variability

Question 35

variability

Answer 35

how spread out the score are in a distribution

Question 36

is variability a descriptive measure or for inferential statistics?

Answer 36

both!

Question 37

how is variability used for descriptive stats

Answer 37

measures the degree to which the scores are spread out or clustered together in a distribution

Question 38

how is variability used fro inferential stats

Answer 38

provides a measure of how accurately any individual score or sample represents the entire population

Question 39

less variability = _____representation

Answer 39

better! when pop variability is small, all of the score are close together, so any indv score or sample will likely provide a good representation of the entire set

Question 40

slide 53?

Question 41

how can you measure variability

Answer 41

range SD/variance both measure distance*

Question 42

SD

Answer 42

average distance between a score and the mean find deviations square deviations sum squared deviations divide by N if pop, n-1 for sample square root

Question 43

a sample with a large SD will look like ____ vs one with a small SD

Answer 43

large SD - wide small SD - narrow

Question 44

a _____ _____ is the basis for inferential statistics

Answer 44

normal distribution

Question 45

how can you analyze where your score falls on your distribution in comparison to others?

Answer 45

convert raw score to z score

Question 46

a score that is located 2 SD above the mean would have a z score of

Answer 46

+2.00

Question 47

formula for converting to z scores

Answer 47

z = score - pop mean / pop SD