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midterm chapters 1-3 Flashcards

1
Q

CH 1-3 STATS

2 Types of Evidence

A

Observational

Evidential

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2
Q

CH 1-3 STATS

Anecdotal evidence

A

Evidence based on short stories or examples of interesting events

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3
Q

CH 1-3 STATS

Confounding variable

A

A variable that correlates with both the independent and dependent variables making it look like the two variables are directly related

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4
Q

CH 1-3 STATS

Placebo

A

An inert substance; a substance that looks like something else but is not composed of the same materials or ingredients
(ex. medicine vs. a sugar pill)

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5
Q

CH 1-3 STATS

Placebo effect

A

The tendency of people to respond favorably to any treatment, even if it is only inert

(Nocebo effect: the tendency of people to respond negatively to any treatment, even if it is only inert)

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6
Q

CH 1-3 STATS

Blinding

A

A technique used to keep the treatment assignment secret from the experimental subject

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7
Q

CH 1-3 STATS

Double-blinding

A

A technique used to keep the treatment assignments from both the experimental subjects and the persons making evaluations of the response

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8
Q

CH 1-3 STATS

Panel bias

A

Bias attributable to the study having influenced the behavior of the subjects

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9
Q

CH 1-3 STATS

Historical Controls

A

Controls are previous patients with the same illness who were treated with a different therapy than the one in question

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10
Q

CH 1-3 STATS

Problem with historical controls

A

Often there is a tendency for later patients to show a better response (even to the same therapy) than the previous patients with the same diagnosis

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11
Q

CH 1-3 STATS

Population

A

All subjects/animals/specimens/plants, and so on, of interest

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12
Q

CH 1-3 STATS

Sample (size n)

A

Subset of the population

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13
Q

CH 1-3 STATS

Effect of a biased sample

A

A biased sample systematically overestimates or systematically underestimates a characteristic of the population

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14
Q

CH 1-3 STATS

Qualifications of a simple random sample

A

a) Every member of the population has the same chance of being included in the sample
b) The members of the sample are chosen independently of each other

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15
Q

CH 1-3 STATS

Qualifications of a nonsimple random cluster sample

A

a) IDs are assigned to entire groups of individuals

b) Entire groups of individuals are selected for the sample

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16
Q

CH 1-3 STATS

Qualifications of a nonsimple stratified random sample

A

a) Population is divided into strata

b) Many random samples are taken-one within each stratum-and combined to comprise the sample

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17
Q

CH 1-3 STATS

Chance error due to sampling (sampling error)

A

A discrepancy between the sample and the population

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18
Q

CH 1-3 STATS

Sampling bias

A

Systematic tendency for some individuals of the population to be selected more readily than others

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19
Q

CH 1-3 STATS

Nonsampling error

A

Error that is not caused by the sampling method; An error that would have arisen even if the researcher had a census of the entire population

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20
Q

CH 1-3 STATS

Nonresponse bias

A

A bias caused by persons not responding to some of the questions in a survey or not returning a written survey

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21
Q

CH 1-3 STATS

Missing data

A

Observations that were planned but could not be made

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22
Q

CH 1-3 STATS

Variable

A

A characteristic of a person or a thing that can be assigned a number or a category

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23
Q

CH 1-3 STATS

Categorical variable

A

A variable that records which of several categories a person or thing is in

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24
Q

CH 1-3 STATS

Ordinal variable

A

A categorical variable in which the categories can be arrayed in a meaningful rank order

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25
# CH 1-3 STATS Numeric variable
A variable that records the amount of something
26
# CH 1-3 STATS Continuous variable
A numeric variable that is measured on a continuous scale (includes decimals, fractions, etc.)
27
# CH 1-3 STATS Discrete variable
A numeric variable for which we can list the possible variables (integers)
28
# CH 1-3 STATS Observational unit
The persons or things on which we are measuring variables
29
# CH 1-3 STATS Frequency distribution
A display of the frequency (number of occurrences) of each value in the data set
30
# CH 1-3 STATS Bar chart
A simple graphic showing the categories that a categorical variable takes on and the number of observations in each category for the data in the sample
31
# CH 1-3 STATS Dotplot
A simple graph that can be used to show the distribution of a numeric variable when the sample size is small
32
# CH 1-3 STATS Histogram
Like a bar chart, except that a histogram displays a numeric variable, which means that there is a natural order and scale for the variable
33
# CH 1-3 STATS Relative frequency
= Frequency / n
34
# CH 1-3 STATS Mode
The central peak in a frequency distribution; the value with the most occurences
35
# CH 1-3 STATS Skewed to the right
The right tail is more stretched out than the left
36
# CH 1-3 STATS Skewed to the left
The left tail is more stretched out than the right
37
# CH 1-3 STATS Unimodal
The graph has only one mode
38
# CH 1-3 STATS Bimodal
The graph has two modes: can indicate the existence of two distinct subgroups of observational units
39
# CH 1-3 STATS Median ( ỹ)
The value that most nearly lies in the middle of the sample--the value that splits the ordered data into two equal halves 1/2 (n+1) denotes the rank position of the median within an ordered data set
40
# CH 1-3 STATS Mean ( ȳ)
Sum of the observations divided by the number of observations (average)
41
# CH 1-3 STATS Robust statistic
A statistic that is relatively unaffected by changes in a small portion of the data (even if the changes are dramatic ones)
42
# CH 1-3 STATS Boxplot
A visual representation of the five number summary
43
# CH 1-3 STATS Five number summary
Minimum, Quartile 1, Median, Quartile 3, Maximum
44
# CH 1-3 STATS First quartile (Q1)
Median of the data values in the lower half of the data set (between the minimum and median)
45
# CH 1-3 STATS Third quartile (Q3)
Median of the data values in the upper half of the data set (between the median and maximum)
46
# CH 1-3 STATS Interquartile Range (IQR)
The difference between the first and third quartiles
47
# CH 1-3 STATS Outlier
A data point that differs so much from the rest of the data that it doesn't seem to belong with the other data upper fence = Q1 - 1.5 * IQR lower fence = Q3 - 1.5 * IQR
48
# CH 1-3 STATS Modified boxplot
A boxplot in which the outliers are graphed as separate points
49
# CH 1-3 STATS Univariate summary
A graphical or numeric summary of a single variable
50
# CH 1-3 STATS Bivariate summary
A graphical summary used to examine the relationship between pairs of variables
51
# CH 1-3 STATS Categorical-categorical relationship graphs
Bivariate frequency table Stacked bar chart Stacked relative frequency bar chart
52
# CH 1-3 STATS Numeric-categorical relationship graphs
side-by-side boxplots | side-by-side dotplots
53
# CH 1-3 STATS Numeric-numeric relationship graphs
Scatterplot
54
# CH 1-3 STATS Scatterplot
A graph that examines the relationships between two numeric variables, X and Y
55
# CH 1-3 STATS Lowless smooth line
A line on a scatterplot that is helpful in visualizing curved or nonlinear relationships in data
56
# CH 1-3 STATS Regression line
A line in scatterplots that is helpful in visualizing linear trends in data
57
# CH 1-3 STATS Range
The difference between the largest (maximum) and smallest (minimum) observations in a sample
58
# CH 1-3 STATS Standard deviation (s)
1. find the deviations for all data points 2. square all 3. add all together 4. divide the sum by n-1 5. take the square root
59
# CH 1-3 STATS Coefficient of variation
The standard deviation expressed as a percentage of the mean (standard deviation / mean) * 100%
60
# CH 1-3 STATS The empirical rule
68% within 1 standard deviation of the mean 95% within 2 standard deviations of the mean >99% within 3 standard deviations of the mean
61
# CH 1-3 STATS Population mean (μ)
= population average value of Y | Y=quantitative variable
62
# CH 1-3 STATS Population Standard Deviation (σ)
=square root (population average value of (Y - μ)^2) | Y=quantitative variable
63
# CH 1-3 STATS Sample Variance (s^2)
Square of the standard deviation (s)
64
# CH 1-3 STATS Effect of addition on the transformation of variables
* Linear transformation * Add constant, c, to the variables * Has no effect on standard deviation
65
# CH 1-3 STATS Effect of multiplication on the transformation of variables
* Linear transformation * Multiply values by constant, c * Multiply standard deviation by absolute value of c

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