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Psychology- Topic 1- Research Methods > Inferential statistics > Flashcards

Inferential statistics Flashcards

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1
Q

What is the range

A

Tells us how dispersed the data is - large range indicates that the data is spread out but a small range depicts the data as close together

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2
Q

What does the variance tell us

A

Tells us about the spread of scores around the mean

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3
Q

What does a small variance mean

A

Implies that the scores are all similar and close to the mean

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4
Q

What does a large variance mean

A

Scores are very different and far from the mean

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5
Q

Preety

A

Dont blame me but I dont have the energy to add any of the population variance and sample variance shit on here bc theres literally no maths symbols

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6
Q

How do you calculate the variance

A

1) Calculate the mean of your scores
2) Find the variance by substracting the mean from each number in your sample
3) Square the result of each calculation
4) Add the squared numbers together to find the sum of squares
5) Divide the sum of squares by n

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7
Q

What is the standard deviation

A

The square root of the variance so it tells us the average amount a number differs from the mean

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8
Q

What does a small standard deviation show

A

That the scores are very similar and consistent

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9
Q

What does a large standard deviation show

A

That the scores are very different and inconsistent

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10
Q

What do you have to do to work out standard deviation

A

Do everything from step 1-5 but square root it

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11
Q

What is the main advantage of both the standard deviation and the variance

A

They take all the scores into account (unlike the range) so are more precise and representative measure of dispersion

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12
Q

Why may the SD be better to use instead

A

It returns the units to the same figure as the mean making it easier to make direct judgements about data sets

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13
Q

What are the weaknesses of the variance and SD

A

It may hide some of the charecteristics of the data which could skew the data

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14
Q

What is a weakness of the SD

A

Because the calculation is based on the mean it isn’t useful when the data is not normally distributed so it lacks usefulness when data is skewed

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15
Q

What are the features of the normal distribution curve

A
  • Bell shaped curve
    The mean median and mode are together in the centre
    50% of scores are on the left and 50% on the right
    Shows that the data set is normally distributed around the mean
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16
Q

What does it mean if data is positively skewed

A

There will be a long tail to the right due to there being extremely high scores pulling the mean to the right

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17
Q

What does it mean if data is negatively skewed

A

There will be a long tail to the left due to there being extremely low scores pulling the mean to the left

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18
Q

What are the 3 levels of measurement

A

1) Nominal
2) Ordinal
3) Interval

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19
Q

What are the features of nominal data

A

Weakest level of measurement
Results are numbers in 2 or more behavioral categories
Shows the number of times something occurred

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20
Q

What are the features of ordinal data

A

Results can be placed in rank order
The difference between each rating rank or score is not known and doesnt have to be equal
Can be calculated using a rating scale question

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21
Q

What are the features of interval data

A

Most precise level of data
Results are made up of numbers that come from a scale of equal or known units with equal distances between the points
Uses precise matematical units like time weight or distance

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22
Q

Which level of data do you use the mode for

A

All can be used but nominal is preferred

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23
Q

Which level of data do you use for the median

A

Ordinal data

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24
Q

Which level of data do you use for the mean

A

Interval data

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25
Q

What are the strengths and weaknesses of nominal data

A

S- easy to generate from closed questions so large amounts of questions can be collected quickly- so increases external reliability
W- Without linear scale participants may be unable to express degrees of response and you can only use the mode as a measure of central tendency which reduces insight so lowers internal validity

26
Q

What are the strengths and weaknesses of ordinal data

A

S- Indicates relative values on a linear scale instead of just totals so its more informative than nominal data so it increases insight so increased internal validity
W- We dont know how large the gap is between the 1st and 2nd place or between 2nd and 3rd or if these gaps are equal- limits usefulness so doesnt enhance knowledge

27
Q

What are the strengths of interval data

A

More informative than ordinal and nominal as the points are directly comparable because they are all of equal value- external reliability increases
Scientists measures used to record the distance between values are highly reliable
internal reliability increased as its standardised
NO WEAKNESSES YES INTERVAL DATA GO YOU GOT THIS

28
Q

What is the probability

A

Refers to how likely something is to happen and is expressed as a number between 0 and 1 or percentage

29
Q

Why is it important to select the level of significance before conducting statistical analysis

A

It indicates how confident a psychologist wants to be about whether the results are significant or just due to chance

30
Q

What does P<0.01 mean

A

The probability the results are due to chance are less than 1%

31
Q

What is a type 2 error

A

It is produced by a strict probability like 0.001 or 0.01
Where we think that there was no effect when there was. Means we accidentally accept the null where we should have rejected it and accepted the research hypothesis
Known as false negative

32
Q

What is a type 1 error

A

Produced by a leniant probability like 0.1 or 0.3.
We think that there is a significant error when really the results were due to chance. May accidentally accept the research hypothesis when it shouldve been rejected and accepted the null. Known as a false positive

33
Q

What are the 5 non parametric tests

A

Mann- Whitney U test
Wilcoxen signed ranks test
Chi squared
Binomila sign test
Spearemans Rho

34
Q

What 3 points do you consider when choosing the appropriate test

A

1) Are you exploring a difference or a correlation between co variables
2) What level of data is collected ( Nom,Ord,int?)
3) What experimental design has been used ( Independent measures)

35
Q

What are the features of Mann Whitney U

A

Exploring difference
Ordinal/Interval data
Independant measures

36
Q

What are the features of Wilcoxen

A

Exploring difference
Ordinal/Interval data
Repeated measures

37
Q

What are the features of Chi squared

A

Exploring difference
Nominal data
Independent measures

38
Q

What are the features of the binomial sign test

A

Exploring difference
Nominal data
Repeated measures

39
Q

What are the features of Spearemans Rho

A

Exploring correlation
Ordinal/interval data
Correlation design is used so co variables are simply measures

40
Q

What is the formula for Mann Whitney

A

Ua= NaNb + Na(Na+1) - Ra
2
Ub=(NaNb)-Ua

41
Q

How do you calculate Mann Whitney U

A

1) Rank all the scores together
2)Add up all the ranks for column A to get the value for Ra
3) Use the formula to calculate

42
Q

How do you rank all the scores together

A

Put all the ratings in ascending order
Next to each rating assign a position
Where there are any dupes work out the mean rank so each score has the same position
Put them back into the table

43
Q

How do you read the critical values table for Mann Whitney U

A

To read the critical vales table we would find the values of Na and Nb and where they meet on the table with the significant level of 0.05 to find our critical value

44
Q

How do you write a significant statement

A

Compare the observed and critical value ( This is because the observed value of 2 is less than the critical value of 5)
Indicate if the results are significant or not at the 0.05 level of significance (refer to N1 and N2 - results are significant at 0.05 level of significance where N1 and N2 equal 6)
Indicate which hypothesis we would accept and which we would reject (Means we can accept the alt hypothesis that there is a sig difference between the effectiveness between A and B and reject the null

45
Q

How do you write a conclusion

A

Indicateif the results are significant or not in context- refer to p value
Make an inference
State which hypothesis we will reject or accept

46
Q

How do you calculate Wilcoxen

A

Find the difference between each set of scores
Rank the difference
Count the number of positive difference and negative differences
Add up the ranks of the least frequent sign

47
Q

How would you rank the data for the calculation of the wilcoxon test

A

I would find the difference between scores for each condition and rank it from lowest to highest. For example….
and place it in order so that — would be the 1st rank and — would have the final rank

48
Q

How would you read the critical values table for Wilcoxon

A

We find the value of N which is the number of differences and see where this value meets the level of significance (0.05) to find the critical value of –

49
Q

What is the formula for the Chi squared test

A

SIGMA observed-expected squared
divided by expected

50
Q

What is the formula for expected frequencies

A

Row total x column total
overral total

51
Q

How do you calculate Chi square

A

Calculate the expected frequencies for each cell using the formula
Use these with the observed frequencies to calculate Chi square using the formula

52
Q

How do you read the critical values table for Chi square

A

I wold use the level of significance which is 0.05 and degrees of freedom which is … and look at the value where they meet which is…

53
Q

How do you calculate degrees of freedom for chi square

A

(number of rows-1)x(number of columns-1)

54
Q

How do you calculate the binomial sign test

A

Assign positive and negative signs depending on the flow of direction
If the participant responses change from yes to no then its positive
If participant responses change from no to yes its negative

55
Q

What is step 2 for binomial sign

A

Count the number of positive and negative signs assigned to each participant
The binomial value is the smallest of the total direction

56
Q

How do you read the critical values table for binomial sign test

A

The level of significance (0.05)
N (the number of participants whose scores were used )

57
Q

What is the Spearemans Rho formula

A

r=1 6 sum of D squares
n(n2-1)

58
Q

How do you calculate Spearmans Rho

A

Rank the scores separately
Find the difference between the ranks
Square the differences between the ranks
Add up the total of the squared differences
Use the formula to work out the final Spearman Rho value

59
Q

How do you read the critical values table for Spearemans Rho

A

You need the level of significance and the number of participants

60
Q

What are the differences for level of significance for all tests

A

Chi square and Spearemans Rho-Less than critical you accept
Rest- reject

Psychology- Topic 1- Research Methods (11 decks)

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