Final Exam Term Review Flashcards
Measurement
the process of comparing a value to a standard
- Distance
- Time
- Force
- Frequency
Reliability
Reproducibility and consistency
Validity
The soundness or appropriateness of a test in measuring what it’s supposed to
Variable
Characteristics of a person, place or thing that can assume more than one value
Constant
A characteristic that does not change
Nominal measurement**
Grouping participants/objects into categories
An example of Nominal measurement**
- Young to old
- Undergraduate Program
- Country of origin
Ordinal measurement
Rank participants/objects
An example of Ordinal Measurement**
Ranking in sports (1st place - 8th place)
Interval measurement**
Equal unit of measurement with no true zero
An example of interval measurement**
Temperature (0 degrees = cold)
Ratio measurement**
Scale that has an absolute zero
An example of Ratio measurement**
- Distance
- Weight
- Mark on an exam
What is interval validity?
A measure of control within the experiment to ascertain that the results are due to the treatment that was applied
What is external validity?
The ability to generalize the results of the experiment to the population from which the samples were drawn
What is a Normal Curve (Gaussian curve)?
- Symmetrical, bell shaped curve
- Measures how frequently scores appear, most frequent towards the middle
- Frequency declines farther from the centre of the graph
What is the Central limit Theorem?
A sum of random numbers becomes normally distributed as more and more random numbers are added together
Types of curves
- bimodal
- Negatively or Positively skewed curve
What is Grouped Frequency Distribution?
- Grouped data into bins (a range of values)
When should grouped frequency distribution be used?
If number of samples is greater than 20 and range is greater than 20
(form 15 groups)
What is a percentile?
A point or position on a continuous scale of 100 such that a certain fraction of the population of raw scores lies at or below that point
Why are percentiles useful?
They use standard scroes that
- evaluate raw scores
- compare two sets of scores that have different units
Mode disadvantages
- unstable and may change
- not useful for further calculations
- ignores extreme scores
Mean
- affected by every other score and outliers can greatly affect it
Relationship of mean, median and mode when data is normally distributed
All three values will fall near or at the same value.
When do you use mean?
- Data is near normal
- Interval or ratio type of measurement
- further calculations are needed (SD)
When to use median
- data is ordinal
- middle score is needed
- most typical score needed
- curve is badly skewed
Use mode when
- only a rough estimate is needed and data is nearly normal
What is variability?
The scatter of scores in a distribution
What is deviance? (d)
Distance of each raw score from the mean
Total sum of deviance
Should equal 0
What is variance? (V or s2)
Average distance between the mean and the data points
What is standard deviation?
The square root of the variance (sensitive to extreme scores)
What is standard deviation used for?
to summarize variability in a data set (easiest to interpret)
What does the standard deviation reflect?
Reflects the deviation from the mean
- most common measure of variability