Statistics Ch. 1-3 First Exam

Observational (descriptive) research

data collected by observing subjects without manipulating any variables.

Correlational research

measuring two variables and assesses the statistical relationship between them.

Experimental Research

includes IV and DP, control group, etc.

Scales of measurement

Nominal: categories; race gender, school major

Ordinal: ranked values; 1st/2nd.3rd place at a race

Interval: each interval (unit of measurement) is the same

Ratio: has a true zero

Descriptive vs inferential stats

Descriptive: describes data

Inferential: draws inferences about a population from descriptive stats of a sample.

Parameters vs. statistics

Paramater: number describing a population

Statistic: describes a sample of a population

Operational Definitions

definition used by person in a specific way.

IV vs DV

independent variable: manipulated, causative agent

Dependent variable: measured, affected by IV

Discreet vs. Continuous

Discreet: specific values, children cats owned

Continuous: all values possible, weight, speed, heart rate

Research Process

1. Theory 1.0

2. Asking research question

3. Formulating hypothesis

4. collecting data

5. analyzing data

6. evaluating hypothesises,

7. theory 2.0

Freqiency Distribution

Frequency = F = How many?

Proportion

P = part of a whole, #/N

Percentage:

the proportion times 100, out of 100.

Cumulative:

C = add to the previous

Raw vs. Cumulative

raw number, number witj previous added

Grouped vs Ungrouped

We can’t list every value possible so we group them into categories,

Highest-lowest+1

Histogrmam

Interval/ration, all rectangles together, height proportional to the frequency/percentage

Bar graph

nominal or ordinal, bars are seperate, height proportional to percentage or frequency.

Line graph:

interval/ratio, points represent frequency of each category, placed above midpoint of category.

Pie Chart:

nominal/ordinal: segments of a circle

Pie and bar graphs: ?

Histogram and line graph: ?

Pie and bar graphs: Ordinal and ratio

Histogram and line graph: interval/ratio

Central Tendency Measures

Mode:most frequent value

Median:the middle value

Mean: all values added up divided by the number of values

levels of measurement for central tendency measures

Mode: all 4

MedianL All but nominal

Means: interval/ratio

Kurtosis

Leptokurtic: pointy

Mesokurtic: normal

Platykurtic: low

Measures of variability

Range, IQR, standard deviation, variance

Range:

highest minus lowest

IQR

the higher median minus the low median

Standard deviation:

the sum of y-mean squared, all divided by N-1, all squared

Variance

standard deviation not squared.

IQV

K(100²-sum of values squared) all divided by 100²(K-1).

Measure of variability for range, IQV, IQR, and variance and standard deviation

Nominal variables: only IQV

Ordinal: IQR or IQV, IQR gives more data

Interval-ratio: all but standard deviation (also variance) provides most information.