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PsychSoc MCAT > Lesson0.2: Statistical Analysis > Flashcards

Lesson0.2: Statistical Analysis Flashcards

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MCAT flashcards
1
Q

Descriptive statistics _________ data. It does not seek __________ within it

A

Describe, relationships

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2
Q

What are descriptive statistics used for?

A

Measures of central tendency and measures of dispersion

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3
Q

What do measures of central tendency do?

A

Estimate the center position of values in a data set

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4
Q

What do measures of dispersion do?

A

Describe how spread out the values of the data are

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5
Q

What is discreet data?

A

Numerical data restricted to certain (usually integer) values
Example: rolling a die, can only yield 1, 2, 3, 4, 5, or 6. You can’t get a 5.6

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6
Q

What is continuous data?

A

Numerical data not restricted to certain number values

Example: the mass of a person can be 63kg, 62.6kg, 62.6523782 kg

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7
Q

What is a uniform distribution?

A

A type of continuous probability distribution where all probabilities are equal
Example: date/time of birth

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8
Q

What is a normal distribution?

A

A type of continuous probability distribution with a bell curve shape
Example: heights of adult Canadian females

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9
Q

All normal distributions have the same properties. Name the 3 properties

A

1) They have a bell shape and are symmetrical
2) The mean is in the center of the distribution
3) The area under the curve is 1

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10
Q

The Y axis in a continuous probability distribution is the …

A

Frequency

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11
Q

The X axis in a continuous probability distribution is the …

A

Variable of interest (e.g., mass)

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12
Q

What is an advantage and disadvantage of using the mean?

A

Pro: it takes all values into account and can thus help minimize error
Con: it takes into account outliers, which can dramatically skew the mean

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13
Q

What does x̄ represent?

A

Sample mean

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14
Q

What does µ represent?

A

Population mean

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15
Q

What is the median?

A

The middle value of an ordered set; the 50th percentile

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16
Q

In what type of data set are the mean and median the same?

A

In a symmetric distribution

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17
Q

Which measure(s) of central tendency can be used with nominal data sets?

A

Mode

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18
Q

Which measure(s) of central tendency can be used with ordinal data sets?

A

Mode, median

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19
Q

Which measure(s) of central tendency can be used with interval data sets?

A

Mode, median, mean

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20
Q

Which measure(s) of central tendency can be used with ratio data sets?

A

Mode, median, mean

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21
Q

What is the most appropriate measure of central tendency for interval or ratio data that are skewed or contain outliers?

A

Median

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22
Q

What is the most appropriate measure of central tendency for non-skewed data?

A

Mean

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23
Q

Measures of dispersion describe …

A

How spread out the data is

24
Q

How is the range calculated?

A

Subtracting the smallest value in a set from the largest value

25
Q

The first quartile Q1 is larger than _____ of the observations

A

25%

26
Q

The third quartile Q3 is larger than ____ of the observations

A

75%

27
Q

How do you calculate the interquartile range (IQR)?

A

IQR = Q3 - Q1

28
Q

What is standard deviation?

A

A statistical measure of variability that indicates the average amount that a set of numbers deviates from their mean

29
Q

What is variance?

A

The square of the standard deviation

30
Q

What does s represent?

A

Standard deviation for a sample

31
Q

What does σ represent?

A

The standard deviation of a population

32
Q

What is considered an outlier?

A

Data that is above Q3 + 1.5IQR or below Q1 - 1.5IQR

33
Q

What causes random error and which measure does it decrease?

A

Caused by human or intstrumental error and decreases precision

34
Q

What causes systematic error and which measure does it decrease?

A

Caused by observer, instrument, or subject bias and decreases accuracy

35
Q

Which type of error is consistent? Random or systematic?

A

Systematic

36
Q

What does accuracy measure?

A

How close the data points are to the actual value

37
Q

What does precision measure?

A

How close the data points are to each other (how well they cluster)

38
Q

What does a correlation coefficient of 0 indicate?

A

That there is no LINEAR relationship

39
Q

What is the difference between correlation and simple linear regression?

A

Correlation does not establish which variable is causing the other. Simple linear regression describes how one variable is associated with another and is an extension of correlation

40
Q

What is a residual and how are they calculated?

A

A residual is the difference between an observed value of the response variable (DV) and the predicted value.

residual = y(observed) - y(predicted)

41
Q

What is a chi-square test?

A

A test used to calculate p-values when all variables are categorical

Example: are people who watch action movies more likely to buy popcorn?

42
Q

What is a t-test?

A

A test used to calculate p-values and compare the average values of a quantitative variable between two categorical groups

Example: is life expectancy different between Canadians and Americans?

43
Q

What is ANOVA

A

A test similar to a t-test but for more than two groups

Example: is the life expectancy different between Canadians, Americans and Mexicans?

44
Q

What is a confidence interval?

A

An estimated range of values, that is likely to include an unknown population parameter at a given confidence level

45
Q

What is the level of confidence?

A

The probability that the interval estimate contains the population parameter

46
Q

What is a Type I error?

A

A false positive: when the null hypothesis is rejected even when it is true

47
Q

What is a Type II error?

A

A false negative: when the null hypothesis is not rejected when it is false

48
Q

What is internal validity?

A

The degree to which the independent variable has been demonstrated to cause the dependent variable

49
Q

What is a threat to internal validity?

A

Confoudning variables

50
Q

How can confounding variables be minimized?

A

Randomization

51
Q

What is temporality?

A

The idea that, for variables to be causally related, the independent variable must occur before the dependent variable

52
Q

What is external validity?

A

The ability of a research design to provide results that can be GENERALIZED to other situations, especially to natural (“real life”) situations

53
Q

Name and describe the two factors external validity depends on.

A

1) The participants included in the sample: they should be representative of the populationto which one wants to generalize
2) The physical realm of the research setting: it should be similar with respect to relevant and important characteristics of the natural situation to which one wants to generalize

54
Q

There is trade-off between ________ validity and ________ validity

A

Internal, external

55
Q

What is the biopsychosocial (BPS) approach and what are the two central tenets of this model?

A

An approach to medicine that integrates psychology, sociology, and biology in diagnoses and treatments

Two central tenets:

1) illness is a product of more than biology (social and psychological factors)
2) illness has multiple causes (genetic, environmental, psychological0

PsychSoc MCAT (2 decks)

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