Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Final Written > Equations And Stats etc > Flashcards

Equations And Stats etc Flashcards

1
Q

How does standard deviation relate to variance

A

Sd is square root of variance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Mean mode median

A

Mean is sum of values / total points
Median is value in series and middle point
Mode is most frequent occurring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are mean median mode effected in normal date, positive and negatively skewed data

A

Normal distribution mean = mode = median
Positive skewed mean > median > mode
Negative skewed mean < median

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is variance and how does it relate to standard deviation

A

Variance is the average of squared differences from the mean

Standard deviation is the square root of variance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Parametric tests

A

2 groups
Paired t
Unpaired t

More than 2
Anova one way
Anova two way

Correlation
Pearson’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Non parametric tests

A

Don’t assume normal distribution
2 groups
Paired wilcoxin rank
Unpaired Mann Whitney

More than 2
Paire freidman
Unpaired Krushall Wallis

Correlation spearman’s rank

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Qualitative data tests

A

Qualitative are all non parametric by default

Up to 2x2
Fishers exact
More than 2x2
Chi squared

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Standard deviations include how much of the distribution

A

1 sad 68%
2 sd 96%
3 sd 99%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Qualitative data

A

Qualitative data is categorical data
Ie ordinal (order ie asa)
Nominal (no natural order ie gender)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Wha5 is statistical variability and what are measures of variability

A

Statistical variability is the spread of the data

Measure of variability usually accompanies measure of central tendency

Small variability = clustered around central tendency

Types
Range
IQ range (ie 25th to 75th centiles gets rid of outliers and is used with median)
Variance (average of the square difference from the mean- all data used)
Standard deviation is square root of variance (mean, v sensitive to outliers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Type 1 error

A

If the null hypothesis is rejected when it is true (ie a false positive the tests shows a difference when there is non)

The risk of this happening is the a risk so sometimes used interchangeably

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Type 2 error

A

Is the null hypothesis accepted when it is false (ie false negative the tests shows no difference when there is one)

The risk of this happening is the B risk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Way to reduce type 1 and 2 error

A

Increase sample size

Power analysis determines the smallest size required

Power = 1-b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Sensitivity

A

Sensitivity of a test is the proportion of true positives of everyone who has the disease

Ie true positives / everyone with disease

Ie true positives / true positives +false negatives

High sensitivity is ulseful for ruling OUT a disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Specificity

A

Specificity is the number of true negatives of everyone who don’t have the disease

Ie true negatives / everyone without the disease

Ie true negatives / true negatives + false positives

Specificity useful for ruling IN a disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Number needed to treat

A

Number needed to treat is a measure of the effectiveness of an intervention

Ie the average no of people treated to prevent or have one outcome

Number needed to treat is the inverse of absolute risk reduction (control group /event group)

Best NNT =1
If no difference between group nnt is inifinity
If nnt less than 0 implies harm

17
Q

Odds ratio and relative risk

A

Odds ratio and relative risk are relative likelihood of an outcome occurring in 2 sample groups

Odds ratio is the ratio of outcome in intervention group compared to outcome in control group

Relative risk is occurrence of intervention group compare to control and requires to know total number of individuals therefore can only do in retrospective studies

18
Q

Predictive values

A

An ideal test positive results is positive for disease and negative result is negative for disease

Test don’t exist like that
The probability that the test will give correct diagnosis is the predictive value of the test

PPV is the proportion of pets with a positive test that actually have disease

Ie true positives / true positives and false positives

NPV is the proportion of people with negative test that actually have the disease

Ie true negatives / true negatives and false negatives

19
Q

Standard error of mean

A

Standard error measures accuracy with which a sample distribution represents a population by using standard deviation. In stats is sample mean deviates from actual mean of population this error is standard error of the mean

20
Q

Risk scores vs risk prediction model

A

Risk scores assign weighting to factors pre identified as inpdenetent predictors out outcome
Get a no at end
Place patient on a scale of risk depending on no
Simple to use
Not that individualised

Risk prediction models put patient variable in and get a probability of risk from the model
More individualised

21
Q

Examples of risk scores

A

ASA
Lees revised cardiac index
Ariscat (pulmonary complications)

22
Q

Examples of risk prediction models

A

P possum
NELA
Sort (surgical outcome risk tool)
ACS NQUIP

23
Q

Lees revised cardiac risk index

A

Risk score development. Africa complications

High risk surgery 
IHD 
CCF 
Cerebrovascular disease 
Insuliapn 
Creatinine over 176

Not generaliseable to low risk or emergency surgery

24
Q

Ariscat

A

Risk score development pulmomary complications

Age 
Sats 
Recent chest infection 
Surgical incision Duration surgery 
Emergency

Negative is ppc are defined in various ways

25
Q

P possum

A

Risk prediction model

Includes 
Age 
Bp 
Heart rate 
ECG 
GCS 
Na 
K 
WCc
Urea

Op severity
Soiling
Malignancy
Blood loss

No morbidity
Over estimates mortality when over 15%

26
Q

NELA j

A

Risk prediction model

Developed from p possum
Accurate and specific for emergency laparotomy

27
Q

Sort

A

Surgical outcome risk tool
Prediction model

Variable 
ASA 
Surgical urgency 
Specialty 
Cancer 
Age 
Severity
28
Q

ACS NSQUIP

A

Risk prediction model

21 variable input, 14 variable output ie VTE pneumonia

Very good
But based on private American population

Final Written (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions