Week 9 Flashcards

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1
Q

What is biostatistics

A

The science of analyzing data and interpreting the results so that they can be applied to solving problems related to biology, health or related fields

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2
Q

What is univariate analysis

A

Describe one variable in a data set using a simplele statistics like counts, proportions and averages

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3
Q

What is multivariable analysis

A

Encompasses statistical tests such as multiple regression models that examine the relationships among three or more variables
( Confounding)

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4
Q

What is a variable

A

Any quantity that varies from one entity to another (sometime within an entity over time)
Any attribute phenomenon or event that can have different values

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5
Q

What are the two sub categories of variables

A

Quantitative and Qualitative

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6
Q

What are the two types of variables in quantitative studies

A

Discrete
Continuous

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7
Q

What are the two types of variables in qualitative sutides

A

Nominal
Ordinal

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8
Q

What is the normal variable

A

No intrinsic or logical order or value
You can assign numbers to different categories
But they do not have any other numeric properties

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9
Q

What is Ordinal variables

A

Intrinsic value but with no clear or equal differences between levels
Mild vs moderate vs severe pain
We can 5 is better than 4 etc but we cannot attribute being measured 4 is not two times larger than 2

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10
Q

How do we display qualitative data

A

Pie chart
Bar chart
Frequency table

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11
Q

Who created the first pie chart

A

Florence Nightingale

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12
Q

What is a numeric variable

A

Any positive real number depends on the nature of the variable can be expressed in decimals
Meaningful numeric scales
Age blood pressure # of friend temperature

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13
Q

What is continuous variables

A

Can take any value
Blood pressure
Temperature
Can be plotted as a line

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14
Q

What is discrete of variables

A

Can take a finite or limited number of variables
Age in year
No of drinks
Can be plotted as dot

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15
Q

What is the Interval variable

A

Interval is the difference is meaningful
No natural zero ( when you have 0 it doesn’t mean nothing)
Arbitrary zero: Interval tempertaure 0 dosen’t mean no 0

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16
Q

What is ratio variable

A

Ratio is meaningful
Zero means absence of attribute ( is natural)
Temperature in Kelvin 0 means absolute 0
Blood pressure a dead person
Age
Income

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17
Q

What are the three aspects of central tendency

A

mean, mode, median

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18
Q

What is the point of histogram

A

Gives you an idea of distribution of all data

19
Q

What is a symmetric normal distribution

A

Mean meidan and mode are the same
This can be Bp
Weight
Height

20
Q

What is negatively skewed normal distribution

A

Mode is on the high side
Mean is low
Marks in modules and tutorial
Means that most people are on the positive end of normal distribution and the outliers are on the other side

21
Q

What is positively skewed

A

The mean is the higher side because you have a few people on the high side like salary where the outliers skew it to the right but most people make a low or moderate income

22
Q

What is the range

A

The difference between the minimum and maximum

23
Q

What are the quartiles

A

Mark three values split the data in half
Q1 is hald of the lower half
Q2 is the median
Q3 is the middle of the upper half

24
Q

How do you calculate interquartile range

A

Q3-Q1

25
Q

What are the main points in a boxplot

A

The first line on the box is Q1
The middle line in the box is the Median
The last line on the box is Q3
The end of the left side is q1-1.5IQR
The end of the right side is q3+1.5
IQR
There are outliers are the dot we don’t want to include them

26
Q

How do you caculate variance

A

You add all your data points minus the mean square it and divide by the amount of numbers

27
Q

How do you calculate standard deviation

A

Is the square root of the variance

28
Q

How do you calculate standard error

A

Dividing the standard deviation by the total number of observations and then dividing by the total number of observations square rooted

29
Q

How is normal curve split up

A

68%
95%
99.75%
Each middle part is 34.1%
Then out is 13.6%
Then 2.1%
Then 0.1%

30
Q

How do you see how many are measured

A

You add mean + 1 sigma
and -1 sigma
Then 2 etc see where you are on the graph

31
Q

What does a confidence interval do

A

Provide information about the expected value of a measure in a source population based on the measured value in a study population

32
Q

What does a 95% confidence interval do

A

Means that 5% of the time the confidence interval is expected to miss capturing the true value of a measure in the source population

33
Q

What is comparative statistics

A

You are comparing 2 groups
Comparing the main factors between exposed and unexposed in cohort studies
We can not just look at the calculated values ( these are estimates from samples subject to random sampling error)

34
Q

What is inferential statistics

A

Techniques that use statistics from a random sample of a population to make evidence-based assumptions (inference) about the values of parameters in the population as a whole

35
Q

What is hypothesis testing

A

To test an explicit statement or a hypothesis about a population parameter

36
Q

What is the null hypothesis

A

There is no difference between the two or more values being compared

37
Q

What is the alternative hypothesis

A

There is a difference between the two or more populations being compared

38
Q

What are the steps in hypothesis testing

A
  1. Take a random sample from the population of interest
  2. Set up two competing hypotheses ( based on research questions)
  3. Use sample statstics (mean,frequency)
  4. Determine if the null hypothesis is really true
39
Q

What is the p value

A

Determine whether the observed sample supports the null

40
Q

When do you reject the null hypothesis

A

If the p value is less than 0.02 or usally less than 0.05

41
Q

When do you accept the null hypothesis

A

0.1 and 0.9

42
Q

How is the p-value caculated

A

From observed data based on pertinent test statistic

43
Q

What is parametric test

A

Assumes the variables being examined have particular distributions
Inferential methods are based on types of distributions
Often normally disturbuted

44
Q

What is a nonparametric test

A

Does not make assumptions about the distributions of reponses
Used for ranked variables and when the distribution of a ratio or interval variable is non-normal