Nursing research DQ # 8

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Chapter 16

Descriptive Statistics

Question

Tell whether the following statement is true or false:

Nominal measurement is the ranking of objects based on their relative standing on an attribute.

Answer

False

Nominal measurement: the classification of characteristics into mutually exclusive categories

Ordinal measurement: the ranking of objects based on their relative standing on an attribute

Measurement

Nominal measurement: the classification of characteristics into mutually exclusive categories
Ordinal measurement: the ranking of objects based on their relative standing on an attribute
Interval measurement: indicating not only the ranking of objects but the amount of distance between them
Ratio measurement: distinguished from interval measurement by having a rational zero point

Descriptive Statistics

Summarize quantitative data
Describe quantitative data

Question

Tell whether the following statement is true or false:

Frequency distributions impose order on raw data. Numeric values are ordered from lowest to highest, accompanied by a count of the number of times each value was obtained.

Answer

True

Frequency distributions impose order on raw data. Numeric values are ordered from lowest to highest, accompanied by a count of the number (or percentage) of times each value was obtained.

Frequency Distributions

Impose order on raw data
Numeric values are ordered from lowest to highest, accompanied by a count of the number (or percentage) of times each value was obtained.
Common methods of display
Histograms
Frequency polygons

Distribution

Symmetric: two halves are mirror images of each other
Skewed: asymmetric with one tail longer than the other
Positively skewed
Negatively skewed
Modality: number of peaks
Unimodal
Multimodal
Normal distribution

Question

What is the median?

Average or typical value of a set of scores

Value that occurs most frequently in a distribution

Point above which and below which 50% of the cases fall

Arithmetic average of all scores

Answer

Central tendency are indexes, expressed as a single number, that represent the average or typical value of a set of scores. The mode is the value that occurs most frequently in a distribution, the median is the point above which and below which 50% of the cases fall, and the mean is the arithmetic average of all scores.

Central Tendency

Central tendency are indexes, expressed as a single number, that represent the average or typical value of a set of scores.
Mode: value that occurs most frequently in a distribution
Median: point above which and below which 50% of the cases fall
Mean: arithmetic average of all scores

Question

Tell whether the following statement is true or false:

Range is the distance between the highest and lowest scores.

Answer

True

Range is the distance between the highest and lowest scores.

Variability

Variability: how spread out the data are
Range: distance between the highest and lowest scores
Standard deviation: indicates how much, on average, scores deviate from the mean
Calculation
Deviation scores represent the degree to which each person’s score deviates from the mean. The variance is equal to the SD squared.

Bivariate Descriptive Statistics

Relationships between two variables
Contingency table two-dimensional frequency distribution in which the frequencies of two nominal- or ordinal-level variables are crosstabulated
Correlation coefficients describe the direction and magnitude of a relationship between two variables.
Product–moment correlation coefficient (Pearson’s r)—interval or ratio
Spearman’s rho coefficient—ordinal
Scatter plot

Risk Indexes

Absolute risk reduction: expresses the estimated proportion of people who would be spared from an adverse outcome through exposure to an intervention
Relative risk: estimated proportion of the original risk of an adverse outcome that persists among people exposed to an intervention
Relative risk reduction: estimated proportion of untreated risk that is reduced through exposure to the intervention

Risk Indexes

Odds ratio: ratio of the odds for the treated versus untreated group
Number needed to treat: estimate of how many people would need to receive the intervention to prevent one adverse outcome