Data Analysis - Module 6

statistical inference

what we know so far

inference

the process of drawing conclusions based on findings from statistical tests

how the inference works in research using statistics

1. collect data
2. data analysis
3. inference about findings

Steps

1. determine point estimate
2. calculate confidence intervals

point estimate

a single number used to estimate the population parameter for confidence intervals

What is the best estimate of population mean??

the sample mean
-we use this single number to calculate the confidence interval

confidence intervals

for the mean specify an interval of values
-our goal is to see if we can estimate a range of numbers from sample data that we can make conclusions about a population

rules

also called assumptions

rules for CI

-normal distribution on bell curve
-interval/ratio (continuous) data required for raw scores

samples less than 60

use critical values for t

samples greater than or equal to 60

use critical values for z

standard error equation

SE = standard deviation / square root of sample size

conclusion statement

______ times (either 95 or 99) out of 100 the mean (insert VARIABLE of interest) will be between _____ and ______.

small standard error

more accurate point estimate thus better chance the population mean is actually close to your sample

large standard error

less accurate point estimate thus a lower chance that the population mean is close to the sample mean