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alevel psychology aqa > inferential statistics > Flashcards

inferential statistics Flashcards

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1
Q
A

using something that can be observed (from a sample) to make an inference about something that cannot be observed (an entire population)

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2
Q

when we analyse our data we assume there is/is no difference between our experimental groups.

A

is no difference

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3
Q

how do we calulate the probability

A

calculate probability of observing differences in sample if there is no difference between populations

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4
Q

As the t-value gets bigger, the probability gets..

A

smaller

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5
Q

If it’s less likely that the null hypothesis is correct, is it more or less likely that the results are due to actual differences between our two experimental groups?

A

more

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6
Q

is the t value is the largest what does that mean about the null hypothesis

A

the null hypothesis is least likely to be correct

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7
Q

As the t-value gets bigger, the probability of observing our results if the null hypothesis is correct gets…

A

smaller

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8
Q

the t value helps us find the probability of….. our results, if the null hypothesis is ……..

A

the t value helps us find the probability of OBSERVING our results, if the null hypothesis is CORRECT

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9
Q

The smaller the t-value, the bigger the probability of the null hypothesis being…

A

incorrect

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10
Q

the t value gets ….. as the probability of observing our results gets …..

A

the t value gets BIGGER as the probability of observing our results gets SMALLER

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11
Q
A
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12
Q

steps for sign test

A

work out type of hypothesis
work out the signs for each number
add up all the pluses and the minuses, discards =
the lowest of the + and - is the S value
N is total minus the equals
find critical value for 0.05
significiance statement

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13
Q

how to word a significance statement for the sign test

A

the s value is…… and which higher/lower/equal to the critical value of ….. wmt the difference is not/is significant

lower/equal is significant
higher is not significant

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14
Q

what could be a reason that data is ordinal and not interval

A

you cannot assume the data is ordinal because eg verbal errors cannot be assumed of equal size

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15
Q

what does p<0.05 mean

A

probability is less than 95% suggesting the results are not due to chance

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16
Q

what are the 3 factors that affect the t value

A

difference between means
dispersion of the data
size of samples

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17
Q

how can the difference between means affect the t value

A

The bigger the difference between the means of two samples, the bigger the t-value

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18
Q

As the difference between the means get bigger, the probability of observing our results if the null hypothesis is correct gets…

A

smaller

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19
Q

the bigger the difference between the means, the …. the probability of observing our results if the null hypothesis is correct.

A

smaller

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20
Q

As the dispersion of the samples’ distributions gets bigger, the t-value gets…

A

smaller

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21
Q

The bigger the dispersion, the … the probability of observing our results if the null hypothesis is correct, and so the …. likely it is that the null hypothesis is correct.

A

bigger, more likely

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22
Q

The bigger the dispersion, the …… the t-value.

A

smller

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23
Q

The bigger the dispersion, the …. likely it is that our null hypothesis is correct.

A

more

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24
Q

The smaller the t-value, the …. likely it is that our null hypothesis is correct.

A

more

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25
Q

The smaller the dispersion, the bigger the probability of observing our results if the null hypothesis is incorrect. true or false

A

true

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26
Q

The smaller the t-value, the more likely it is that our null hypothesis is correct. true or false

A

true

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27
Q

The bigger the dispersion, the less likely it is that our null hypothesis is correct. true or false

A

false

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28
Q

As the sample size increases, the t-value gets..

A

biggger

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29
Q

As the sample size gets bigger, the probability of observing our results if the null hypothesis is correct gets…

A

smaller
so the less likely null is correct

30
Q

As the sample size decreases, it becomes ….. likely our null hypothesis is correct.

A

more

31
Q

probabilities are always expressed as either…

A

fractions
percentages
a number between 0 and 1

32
Q

If a t-value gives a probability of 0.03 this means there is a …. probability of obersving our results if the null H is ….

A

3%
correct

33
Q

If a t-value gives a probability of 12% this means that there is a …. probability of observing our results if the null H is ….

A

12%
correct

34
Q

what is p value

A

probability of observing our results if the null hypothesis correct

35
Q

what does a p=56% mean

A

if the null hypothesis is correct, there is a 56% probability of observing our results

36
Q

a bigger t value gives a …. p value

A

smaller

37
Q

As the p-value gets smaller, is the null hypothesis more or less likely to be correct?

A

less

38
Q

Grace and Ruby carry out separate experiments. Grace gets a p-value of 17% and Ruby gets a p-value of 13%. Who is more likely to reject the null hypothesis?

A

ruby

39
Q

As the p-value gets bigger, there is a bigger probability of observing our results if the null hypothesis is correct. True or False?

A

true

40
Q

James and Sophie carry out separate experiments. James gets a p-value of $0.04$ and Sophie gets a probability of $4\%$. Who is more likely to reject their null hypothesis?

A

equally likely

41
Q

what do we use a t test for

A

to decide whether to accept or reject our null hypothesis

42
Q

how do we know what size of p value will mean accept or reject thenull H

A

the experimenter decides at the begining of the study, they create a significance level

43
Q

If a researcher decides on a significance level of 5% for their experiment, then they will decide that their null hypothesis is incorrect if they obtain a p value of

A

5% or less

44
Q

What is the name of the value at which a researcher switches from accepting the null hypothesis, to rejecting it?

A

significance level

45
Q

If the p-value a researcher obtains is smaller than or equal to the significance level that they selected, then they…

A

reject the null H

46
Q

If Jack sets his significance level at 20 %
and then obtains a p-value of 19.9% in his study, can he reject the null hypothesis?

A

Yes, because his p-value is below the significance level.

47
Q

A type 1 error is when researchers…

A

incorrectly reject the null hypothesis, and say there is a real difference between two experimental groups when there isn’t one.

48
Q

if a researcher chooses a significance level of 15% what is the proability of making a type 1 error

A

15%

49
Q

what does the significance level tell us

A

how likely we are to make a type 1 error

50
Q

as the significance level gets smaller is it more or less likely that type 1 errors will occur

A

less likely

51
Q

if researchers dont want to cause any type 1 errors what might they do

A

set the significance level really low

52
Q

if a the significance level is low what is less likely to happen in regards to the null H and type 2 error

A

it is less likely itll be rejected

and increases possibility of a type 2 error

53
Q

what is a type 2 error

A

failure to reject the null hypothesis when there actually was a difference between experimental groups

fail to reject the null hypothesis, and say there isn’t a difference between the two experimental groups and conclude their results happened by chance when there actually is a difference

54
Q

To balance the risk of a Type 1 and Type 2 error, what value do we usually set the significance level at?

A

5%

55
Q

setting SL at 5% means what in terms of nullH

A

we reject the null hypothesis is theres less than 5% probability of it being correct

56
Q

Petra is investigating the effectiveness of reading on patients with anxiety. She selects a significance level of 5% and obtains a p-value of 0.05. She rejects the null hypothesis

typ1, 2 or no error

A

none

57
Q

. Osman is investigating the effectiveness of consistent sleeping patterns on patients with depression. He selects a significance level of 0.06% and obtains a p-value of 0.06. He fails to reject the null hypothesis, even though consistent sleep patterns were actually effective for many patients.

1,2 or no error

A

2

58
Q

Kate is investigating the effectiveness of exercise on memory recall. She selects a significance level of 10% and obtains a p-value of 8%. She rejects the null hypothesis, even though exercise didn’t actually improve memory recall.

1, 2, no error

A

1

59
Q

Hanna is investigating the effect of pets on happiness levels for people with depression. She sets the significance level at $0.11\%$, but accepts her null hypothesis. Which error is most likely to have occurred?

A

2

60
Q

If a researcher sets their significance level at 5% and gets a p-value of 14% should they reject the null hypothesis?

A

no

61
Q

What is the name of the probability of observing our results if the null hypothesis is correct?

A

p value

62
Q

Jack sets his significance level at 5% and obtains a t-value (t=2.178). The critical t-value for his significance level is t=2.086. Can Jack reject the null hypothesis?

A

Yes, because his obtained t-value is bigger than the critical t-value.

63
Q

We reject the null hypothesis if the obtained t-value is…

A

bigger than, or equal to, the critical t-value for our significance level.

64
Q

as the sample size increases what happens to the t value

A

it increases

65
Q

For the unrelated t-test, what is the degrees of freedom?

A

The total sample size across the two groups subtract 2

66
Q

For the related t-test, what is the degrees of freedom?

A

For a related t-test, the degrees of freedom is the sample size subtract 1

67
Q

when is an alternative hypothesis needed

A

when we reject the null hypothesis

68
Q

if the null hypothesis was: no different between heights of first borns and second borns.

and it was rejected, what would the alternative hypothesis be

A

first borns are taller than second borns

69
Q

the alternative hypothesis is the hypothesis that is our results are …..

A

unlikely to have happened by chance and there is a real difference between the experimental groups

is the opposite of the null hypothesis.

70
Q

which is one tailed, which is two tailed

A

directional is one tailed

non directional is two tailed

71
Q
A

alevel psychology aqa (38 decks)

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