EBP Ch 6 pt 2

define raw data

raw data is the info we collect before organizing it in a meaningful way

ex: writing down the ages of 100 ppl

define frequency distribution

frequency distribution is a table which indicates how many ppl in a sample fall into each category

what type of distribution involves categorical/nominal variables

frequency distribution

what type of distribution use bar charts to represent their data

frequency distribution

define grouped frequency distributions

grouped frequency distributions puts # into ranges instead of listing out every possibility

what type of distributions involves continuous data

grouped frequency distribution

what distribution uses histograms to represent their data

grouped frequency distribution

define a frequency curve

a frequency curve is basically a grouped frequency distribution but instead of bars, they use lines

what distribution is most useful at representing trends in data

frequency curve

define descriptive statistics

these are numbers we use to summarize and describe our data

what are the measures of central tendency

mean, median mode

define dispersion/spread

dispersion/spread tells us how spread out the data is

define the mean

-the average

-there is only 1 in a data set

-it is affected by outliers

define the median

-the middle #

-there is only 1 in a data set

-used in skewed distributions

define the mode

-the most frequent #

-there can be multiple in a data set

-it is NOT affected by outliers

define distribution

-the overall pattern of scores

-normal distributions are symmetrical and bell-shaped

-in normal, the measures of central tendency will all fall at the top point of the curve

what measure of central tendency is affected by outliers

mean

what measures of central tendency is not affected by outliers

mode

define outliers

outliers are extreme scores in a distribution which can make the pattern look uneven or skewed

describe skewed distributions

-skewed distributions can be positively skewed (exam scores) or negatively skewed (ages at death)

-the measures of central tendency will fall at diff points

how will skewed distributions look

the median will always be bt the mean and mode. the mean will be closer to the tail

describe the dispersion/spread

dispersion/spread says that a curve that is tall/skinny means that the data is close to the measures of central tendency, while a curve that is short/wide means the # are more spread out w variability

define the range

-most simple measure of dispersion and least useful

-(highest # - lowest # = range)

define variance/s²

-another type of dispersion

-uses all the scores in a data set to calculate the amount of variation from the mean (in squared units)

-used to find the standard deviation (s)

define standard deviation/s

-most common way to measure dispersion

-like variance, it tells us how far scores are from the mean in simple terms

-square root of s² = s

what does a small/big standard deviation tell us

small s: scores are close to the mean

big s: scores are more spread

define the empirical rule

the empirical rule tells us approximately how much data falls within 1, 2, or 3 standard deviations of the mean in a normal distributions

68% scores fall within ( ) s of the mean

95% scores fall within ( ) s of the mean

99% scores fall within ( ) s of the mean

68% = ±1

95% = ±2

99% = ±3

what is the purpose of margin of error and how do we minimize it

when we collect data from a sample, the results may not perfectly match up w the whole population.

we use margin of error it to see how far our sample results could be from the actual population results. we do this by INCREASING THE SAMPLE SIZE