Midterm

Question 1

Median calculation

Answer 1

L + (.5N - Nb /nw)i

Question 2

Percentile calculation

Answer 2

Nw(X - L) + (Nb *i) / Ni

Question 3

X value from a %

Answer 3

L + (. %N - Nb / nw)i

Question 4

Properties of variance /SD as a measure of variability

Answer 4

Always +
If all the scores are the same these values will be 0
Variance is more sensitive to deviations from the mean, since the values are squared

Question 5

Stem and leaf

Answer 5

Combines elements of a histogram, freq distribution, and cum freq that retains more detailed information about the data

Question 6

Cum freq

Answer 6

Distribution where the entry for a score value is the sum of all the freqs at that value plus all the scores below it

Question 7

Validity

Answer 7

How well a study or measure does what it is supposed to do. It’s the extent in which the measurement accurately reflects the conceptual variable being measured

Question 8

Variance

Answer 8

The degree of variability in a group of scores, found by squaring the deviations about the mean and dividing by the number of scores in the distribution

Question 9

Normal distribution characteristics

Answer 9

Bell-shaped, unimodal, mean mdn and mode all have the same value, theoretical distribution based on a population od infinite # of cases, the tails are asymptotic (never reach 0), symmetrical about the central point having an equal # of cases about and below

Question 10

Fourth-spread

Answer 10

25-75% Range of scores in the middle half of the batch