Statistics

Question 1

denominator

Answer 1

name for the bottom half of a formula

Question 2

descriptive

Answer 2

Statistics that describe an aspect of data (e.g. mean, median, mode, variance, range)

Question 3

inferential

Answer 3

Statistics that allow you to make predictions about or comparisons between data (e.g., t-value, F-value, rho)

Question 4

interval estimates

Answer 4

a range of values that summarise an aspect of a data set. Examples include the range, variance, standard deviation, standard error and confidence intervals.

Question 5

mean

Answer 5

A descriptive statistic that measures the average value of a set of numbers

Question 6

median

Answer 6

The middle number in a distribution where half of the values are larger and half are smaller

Question 7

numerator

Answer 7

name of the top half of a formula

Question 8

participant

Answer 8

the word used to describe someone who has taken part in a study. Note that subject is outdated and no longer used

Question 9

point estimates

Answer 9

a single value that summarises an aspect of a data set. Examples include the mean, median, and the mode.

Question 10

population

Answer 10

All members of a group that we wish to generalise our findings to

Question 11

sample

Answer 11

a subset of the population that you wish to make an inference about through your test

Question 12

Parametrics

Answer 12

Rules or assumptions about the data that must be confirmed before we use a specific test, otherwise the findings would be meaningless. Examples: t-tests, pearson correlation, single regression, multiple regression

Question 13

Spread

Answer 13

Degree of dispersion (variability) of values in a dataset

Question 14

Range

Answer 14

least informative, lowest value to highest value

Question 15

Interquartile Range

Answer 15

summarising values between the 25th and 75th percentile and captures 50% of the distribution

Question 16

Variance

Answer 16

a measure of spread which uses information from all the scores in a dataset - averaged squared deviated from the mean
steps of calculation:
1. Find the difference between value and the mean
2. square the difference
3. sum all the squared differences together
4. Divide by N-1

Question 17

Standard Deviation (SD)

Answer 17

measure of the average deviation from the mean in the original scale, using all the values in the data set
steps of calculation:
1. Find the difference between each value and the mean.
2. Square each difference
3. Sum all the squared differences together
4. Divide by N-1
5. Take the square root

Question 18

Standard Error of the Mean (SEM)/(SE)

Answer 18

A statistical measure that describes how much the sample mean is expected to vary from the true population mean
calculated by dividing the SD by the square root of the number of values

Question 19

Probability

Answer 19

the likelihood of the occurrence of an event or outcome

p = number of ways the event could arise/number of possible outcomes

Question 20

joint probability

Answer 20

the unrelated events occurring at the same time. calculated by multiplying together the probability of each individual event

Question 21

replacement

Answer 21

resetting the number of outcomes to the original value after an event occurs

Question 22

Binomial distribution

Answer 22

a discrete distribution in which every event has a probability on a given distribution

A statistical distribution that summarises the probability that a value will take one of the two independent values under a given set of parameters or assumptions

Question 23

Normal distribution

Answer 23

a theoretical distribution with a particular bell shape. the peak of the distribution corresponds to the mean, mode, median = 0 and the SD = 1

Question 24

Null hypothesis significance testing (NHST)

Answer 24

A technique for establishing if a hypothesis is likely based on the probability of finding a value as large as or larger, than the one you have found, if the null hypothesis was true

Question 25

null hypothesis

Answer 25

there is no difference or relationship

Question 26

level of significance (alpha)

Answer 26

the probability level at which we reject the null hypothesis, usually a = .05

Question 27

Rejection region

Answer 27

a portion of a sampling distribution which includes samples with probabilities less than alpha

Question 28

z-score

Answer 28

the number of standard deviations any particular score is away from the mean

calculated by subtracting the mean from the value and dividing it by the SD

Question 29

one sample chi-square test

Answer 29

method of investigating the probabilities of values being in specific categories/groups. used when dealing with frequencies rather than scores. Assumes independents samples and nominal scale data (categorical data).

Question 30

observed frequencies

Answer 30

counts per category, expected: most basic approach is equal likelihood of each option

Question 31

expected frequencies

Answer 31

represent a uniform frequency distribution expected under H0 (no preference)

Question 32

degrees of freedom

Answer 32

the number of observation (units/data points) that are free to vary to produce a given outcome

for one sample chi square calculated as: k-1 (k is number of conditions)

for cross tabulation chi squares: calculated as (R-1) * (C-1) where R refers to number of rows and C to number of columns

Question 33

effect size

Answer 33

a common effect size for the chi quare test is phi. it is a standardised measure of the difference of interest that is comparable across experiments that use different N

Question 34

alpha

Answer 34

pre-determined level of significance at which we agree to reject the null hypothesis

Question 35

p (p-value)

Answer 35

the probability of finding a test statistic as large or larger than the one found in your study, if the null hypothesis were true

Question 36

cross tabulation chi square tests

Answer 36

tests whether variable A and B are related in producing the observed frequency distribution