Flashcards in Statistics Deck (30):

1

## what are descriptive statistics?

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they describe samples of the population in terms of numbers

they include means, medians, SD, Z-scores and Percentages etc

Generally descriptive statistics should be given to 2 D.P.

2

## what are inferential statistics?

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they infer meaning from our samples.

Include Pearson's R, the Mann Witney test and the T-test.

3

## what is interval data?

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this is data with similar intervals between them (like a ruler)

e.g calorie intake

4

## What is ratio data?

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ratio is very similar to interval data except it has an absolute 0 value.

e.g a memory test.

5

## what is Variance?

### It is the measure of average deviation of the scores from the mean score. The bigger the variance the more spread there is around the mean

6

## What is the interquartile range?

### this is the range of scores of the middle 50%

7

## what are Z scores?

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a z score is probability of density function.

a Z score will tell you how many standard deviations your score is from the mean

they can be negative or positive

8

## what are the parametric assumptions?

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1. it needs to be interval/ ratio level data

2. data needs to be normally distributed

3. homogeneity of variance/ sphericity ect

9

## what is homogeneity of variance?

### The assumption of homogeneity of variance is that all comparison groups have the same variance.

10

## What is sphericity ?

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Sphericity applies to a repeated measures design. It is the condition where the variances of the differences between all combinations of related groups (levels) are equal

11

## What are Psychometric tests??

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these are implicit tests for implicit psychological measures and unconscious aspects of human nature.

they are useful as they try to avoid response bias

12

## Name a few types of psychometric tests.

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1. Attitude questionnaires

2. word association tests

3. semantic differential tests (type of attitude scale)

4. implicit tests e.g IAT

13

## what are the problems with attitude questionnaires?

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1. the Normative response bias: people give answers that are considered right or normal e.g I always tell the truth

a lie test can be used to combat this

2. social desirability effect

3. Ambivalence- people can report both positively and negatively for the same attitude

4. inconsistency

14

## Evaluate word association tests.

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1. they are easy and cheap to administer

2. they can be used to predict drug use (Ames et al)

3. they can be self scored which improves validity

4. colloquialism- words that are drug related in one area may not be drug related in another

5. implicitness is questionable?

15

## What is the IAT- implicit association task

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it is used to measure association between concepts.

widely used in social research- e,g prejudice ( age race gender)

16

## evaluate the IAT.

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1. Suggested it measures cultural views rather than personal beliefs

2. lacks ecological validity- cannot be generalised to real life.

17

## what are correlations?

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a correlation is a relationship between two variables..

they are specific models that allow us to make inferences about the population

18

## what is the difference between Spearman's and Pearson's correlations

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Pearson's R correlations only look at linear data and are very powerful

Spearman's Correlations can look at non-linear data

19

## what is the equation of a straight line?

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y= bx + a

b is the gradient of the line

a is the intercept

20

## what is a model?

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a model is made of data and some form of natural function that can explain the outcome

e.g a model can be Pearson's r correlation coefficient or a regression line

21

## what does Pearson's R particularly assume?

### the assumption of Linearity.

22

## what is Cronbacks alpha?

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this is a test that splits items equally in every way possible

it then correlated all halves with all other halves

it is a very robust measure of internal reliability.

23

## what is convergent validity ?

### this is comparing your test to a similar test- A HIGH CORRELATION INDICATED VALIDITY.

24

## what is divergent validity?

###
correlating your study to an unrelated construct.

if you are looking to measure depression, a high correlation with an anxiety questionnaire would make your depression scale less valid.

25

## What is a type 1 error?

### When the null hypothesis is rejected when it should be accepted

26

## What is a type 2 error?

### This is when the null hypothesis is accepted when it should be rejected

27

##
What is interpolation?

(Regression lines)

### Reading off values of y from any given value of x

28

## What is extrapolation

### We extrapolate data when it goes on past the plotted data values

29

## Summarise and Evaluate regression models..

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They have a predictive utility. They can be used to look at multiple predictor variables.

30