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acs 401 > Midterm > Flashcards

Midterm Flashcards

1
Q

Descriptive Statistics

A

Brief descriptive coefficients that reflect either a sample or a population (e.g. mean)

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2
Q

Inferential Statistics

A

Techniques used to draw inferences about the population from a sample (e.g. estimation)

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3
Q

Population

A

Complete collection of all elements of the researcher is interested in (e.g. average age of all first-year students in Canada)

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4
Q

Sample

A

Subset of members selected from the target population (e.g. all first-year students in Canada)

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5
Q

Cases

A

The entities from with the data is gathered to make up your sample (e.g. one first-year student in Canada)

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6
Q

Variables

A

Traits that can change values from case to case (e.g. age)

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7
Q

Discrete variables

A

Measured in units that cannot be subdivided (e.g. sex)

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8
Q

Continuous variables

A

Measured in a unit that can be subdivided infinitely (e.g. age)

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9
Q

What are the levels/scales of measurement?

A

Nominal, ordinal, interval, ratio

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10
Q

What is a nominal level of measurement?

A

Only named, no quantitative value (e.g. sex)

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11
Q

What is an ordinal level of measurement?

A

Attributes can be ordered (e.g. 1st, 2nd, 3rd place in a race)

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12
Q

What is an interval level of measurement?

A

Measuring on a scale that has equal units through its scale (e.g. temperature) - negatives

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13
Q

What is a ratio level of measurement

A

Ranks categories in terms of differences in magnitude, absolute 0 (e.g. speed) - no negatives

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14
Q

What is proportion and how do you calculate it?

A

Compares part to the whole, P=f/N

where f is part, N is the whole

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15
Q

What is ratio and how do you calculate it?

A

A number calculated by dividing the number of cases in one category by the number of cases in another, R=f1/f2
where f1 is the smaller category, f2 is the bigger

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16
Q

What is rate and how do you calculate it?

A

The number of occurrences of an event/characteristic divided by the number of possible occurrences per unit of time (typically multiplied by a larger number e.g. 1000, 10,000). R=(f1/f2)x the given number

17
Q

What is percent change and how do you calculate it?

A

Measures the magnitude of change in a variable from time 1 to time 2 (relative increase/decrease over time)
PC=(f2-f1/f1)x100

18
Q

What is skewness?

A

When a distribution has a few very high or very low scores, the mean will be pulled in the direction of the extreme scores.

19
Q

What does a positive/right skew occur?

A

When the mean is greater than the median

20
Q

When does a negative/left skew occur?

A

When the mean is less than the median

21
Q

When is there no skew?

A

When the mean is equal to the median

22
Q

What are percentiles?

A

Indicate the relative standing of a person or object within a whole distribution. Split a set of ordered data into hundredths

23
Q

How do you calculate percentiles?

A

i=P/100(N+1)

1) rank values from lowest to highest
2) calculate which rank is the percentile using the formula

24
Q

What is inter-quartile range and how do you calculate it?

A

A measure of spread or dispersion - the difference between the 75th percentile (Q3) and the 25th percentile (Q1).
IQR=Q3-Q1
- to find Q1, find the “median” of the scores above and below the real median

25
Q

What is variance and how do you calculate it?

A

The average squared deviation of values from the mean value

  • I can’t put the formula in here, but basically:
    1) calculate mean
    2) subtract mean from each score then square
    3) sum
    4) divide sum by (n-1)
26
Q

What is standard deviation and how do you calculate it?

A

Represents the average distance of a set of scores from the mean

  • I can’t put the formula in here, but basically:
    1) calculate mean
    2) subtract mean from each score then square
    3) sum
    4) divide sum by (n-1)
    5) take the square root of the quotient
27
Q

What is the coefficient of variation and how do you calculate it?

A

The ratio of the standard deviation of a distribution to its arithmetic mean
CV=(SD/sample size)x100

28
Q

What is kurtosis?

A

Measures the degree of “peakedness” of a distribution.

29
Q

What is positive kurtosis?

A

Observations cluster more at the centre and have longer tails

30
Q

What is negative kurtosis?

A

Observations cluster less and have shorter tails

31
Q

What is leptokurtic?

A

Distribution with a high peak

32
Q

What is platykurtic?

A

Distribution with a low peak

33
Q

What is mesokurtic?

A

Normal distribution

34
Q

What are z-scores?

A

The position a particular value of x in relation to the mean, measured in SD units.

35
Q

How do you calculate z-score from a raw score?

A

z=(value-mean)/SD

36
Q

What are parameters?

A

Mathematical characteristics of populations, estimated through statistics

37
Q

What are statistics?

A

Mathematical characteristics of samples

acs 401 (2 decks)

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