Descriptive statistics Flashcards

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1
Q

Measures of central tendency definition?

A

the relationship of the values with the central point

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2
Q

Least to most precise/ sensitive MOCT

A

mode -> median -> mean

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3
Q

how to calculate mean ?

A

= the average

add up all numbers/ number of numbers

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4
Q

how to calculate mode?

A

= most common number, may be more than 1

putting similar scores together, and counting which appears most frequently

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5
Q

median calculate?

A

= central value

- arranging scores in order and finding mid point

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6
Q

advantages of the mean?

A

+ appropriate to use for further statistical analysis such as standard deviation
+ appropriate to use for ordinal, interval, ratio levels of data

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7
Q

mean disadvantages?

A
  • affected by extreme scores so can misrepresent no.s

- may produce a value that no ppt in the data set achieved

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8
Q

mode advantages?

A

+ unaffected by extreme scores
+ can be used with nominal (categorical data) & provides info abt freq
+ unlike mean and median, there is always a modal score

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9
Q

mode disadvantages?

A
  • ignores values by only looking at the freq of no.s, this may lead to biased representation as an outlier score may be the most frequent
  • can be unclear as data may have several modes - bimodal = 2
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10
Q

median advantages?

A

+ makes use of all the values but is not as biased by extreme scores as mean
+ can be used with ordinal data

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11
Q

median disadvantages?

A
  • more open to bias from extreme scores than mode

- unhelpful for further statistical analysis such as standard deviation

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12
Q

what is measures of dispersion?

A

how dispersed or spread out the data are

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13
Q

range calculated?

A

the range is a measure the spread of a set of scores, shown by the difference between highest and lowest

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14
Q

standard deviation?

A

measure of the spread of data around th mean.

higher value = more variation in your scores

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15
Q

range +?

A

+ easier to calc than standard deviation

+ takes into account extreme values

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16
Q

range -?

A
  • affected extreme values and does not take into account the no. of observations in the data set
  • it does not give info on whether the scores are clustered around the mean or spread out
17
Q

SD +?

A

+ Gives more precise and informative measure of dispersion than range, as it doesn’t just take into account highest & lowest
+ less affected by anomalous results than range - extreme scores are ignored

18
Q

SD -?

A
  • more complicated to calculate then range

- can only be used when data set is normally distributed (bell shaped curve) and not skewed

19
Q

What is meant by low standard deviation?

A

Data is clustered around average

20
Q

what is meant by high standard deviation?

A

Tells us data is dispersed

21
Q

When is SD used?

A

When distribution of data is approx normal- a bell shaped curve
To tell when data is normal, expected, unusual

22
Q

What is the 68-95-99.7 rule?

A

About 68% of data falls within the 1st sigma
About 95% of the data falls within the 2nd sigma
About 99.7% of data falls into 3rd sigma

23
Q

Acting with the mean SD allows us to determine whether

A

A value is statistically sig or as a part of standard deviation (expected)